Who will be Senate Majority Leader when the 120th Congress convenes in January 2027?

As of October 15, 2026, Chuck Schumer is the most likely Senate Majority Leader in January 2027, at 48 percent, up from 46, ahead of John Thune at 32. Our Senate forecast gives Democrats a 66 percent chance of control, and Axios reports Schumer is more than favored to win the caucus secret ballot.

Evidence cutoff October 15, 2026Version 3 of 3By the TPG Forecast Desk, edited by Frank Carrasco, PhD#c02863dc46

Why it matters: The Majority Leader controls what reaches the Senate floor, including judges, cabinet nominees, war powers votes and any deal with a Democratic House, for the final two years of President Trump's term.

May be out of date. This forecast's evidence stops on October 15, 2026, 25 days ago. The desk reviews stale forecasts first; a new version will appear here when the evidence moves.

TPG forecast: most likely

Chuck Schumer

48%

Schumer favored, Thune second

Chuck Schumer48%
John Thune32%
Brian Schatz8%
Chris Van Hollen5%
Someone else3%

Our odds over timeTPG forecastMarket

Version 3: 48% (range 36% to 56%)

Evidence cutoff Oct 15, 2026 · published Oct 15, 2026 · Schumer favored, Thune second

The field

Every contender, the odds, and the record on paper. Record facts are sourced; we forecast who is most likely to win, not who should.

01Chuck SchumerDemocratic

Senate Minority Leader, Senator from New York

45 years in high office

48%

Leadership record: Senate Democratic leader since 2017; Majority Leader 2021 to 2025[9]
Insider read, August 2026: Senate Democratic insiders say he is likely to remain leader[4]
Opposition from 2026 nominees: Nominees in Michigan, Minnesota and Maine say they will not vote for him[5]

The caseHe has led the caucus for nearly a decade, recruited the candidates who are putting Republican seats in play, and a leader who wins back the majority is rarely removed.

The riskSeveral new Democratic nominees have pledged to vote against him, and if the new majority is narrow, a handful of defections could force him out.

02John ThuneRepublican

Senate Majority Leader, Senator from South Dakota

27 years in high office · elections 0 won, 1 lost

32%

Leadership record: Senate Majority Leader; previously Senate Republican Whip[10]
2024 leadership election: Defeated John Cornyn and Rick Scott[3]
Plans for November leadership vote: "The assumption is yes"[1]

The caseIf Republicans keep the Senate he is the clear favorite to stay, since no viable rival has emerged and Rick Scott says he will not challenge him again.

The riskOur desk gives Republicans only a 34 percent chance of keeping the Senate, and a disappointing result could invite a challenge from the party's MAGA wing.

03Brian SchatzDemocratic

U.S. Senator from Hawaii, Chief Deputy Whip

24 years in high office

Whip race: Has locked up the votes to become Senate Democratic whip[6]
Succession standing: Viewed as Schumer's preferred successor[13]

The caseAs whip-in-waiting and Schumer's preferred successor, he is the natural choice if Schumer steps aside after a Democratic win.

The riskProgressives who want to break with the Schumer era may see him as too close to the current leadership.

04Chris Van HollenDemocratic

U.S. Senator from Maryland

35 years in high office

Senate service: Elected to the Senate in November 2016[14]
Succession standing: Name most often floated by progressives[7]

The caseHe is the progressive wing's most discussed alternative and has declined to commit to backing Schumer beyond 2026.

The riskHe has not declared any challenge, and challengers to a sitting Senate leader rarely win.

05Someone else

Any senator not listed, including Cory Booker, Chris Murphy, Amy Klobuchar or a Republican challenger to Thune

The caseLeadership races can turn quickly after a surprise election result, as Trent Lott's sudden exit in 2002 showed.

The riskSenate caucuses almost always elect a sitting leader or the next person in line.

06Catherine Cortez MastoDemocratic

U.S. Senator from Nevada

18 years in high office

Succession standing: Growing buzz as a more centrist option[11]

The caseA centrist from a swing state with a strong fundraising network could be a compromise pick if the caucus splits between Schatz and a progressive.

The riskShe has no leadership post today and no public campaign for one.

07John BarrassoRepublican

Senate Majority Whip, Senator from Wyoming

23 years in high office

Leadership role: Senate Majority Whip, the No. 2 Republican[15]

The caseAs the second-ranking Republican, he is the most likely replacement if Republicans hold the Senate but Thune steps aside.

The riskThune intends to run again and no rival has emerged.

The numbers behind the call

net seats Democrats must gain to win the Senate[17]

22 vs 13

Senate seats Republicans vs Democrats are defending in 2026[18]

Since 2017

Schumer has led the Senate Democratic caucus[9]

Schumer's age; insiders still expect him to remain leader[4]

58.6%

Democratic Senate chance in Nate Silver's model on September 14 (dated; our forecast has since moved)[16]

What it means for you

People following the courts

A Majority Leader Thune keeps confirming the president's judicial nominees. A Democratic leader, whether Schumer or a successor, would decide which nominees get a vote at all.

Military families and foreign policy watchers

A Democratic leader could schedule votes to limit the Iran war and hold more oversight hearings. A Republican leader would keep that agenda aligned with the White House.

Progressive and centrist Democrats

If Democrats win but replace Schumer, the choice between a leader like Brian Schatz or Chris Van Hollen signals how far left the caucus will push on taxes, health care and Israel policy.

Taxpayers

Only a Republican Senate paired with a Republican House can pass another party-line tax bill through reconciliation. A Democratic leader ends that path through 2028.

The read

Three lenses, always in this order. How the method works.

Psychology

What do the decision makers need?

Senators choose their leader in a private vote after the election, and their main question is who can protect and expand the majority. Schumer's allies argue that if Democrats win back the Senate he will have earned another term, and he has kept campaigning alongside nominees who say they will not back him. The nominees, for their part, made the pledge to win progressive primaries; once elected, the cost of keeping it depends on whether an alternative candidate exists and how narrow the majority is.

On the Republican side, Thune told Roll Call 'the assumption is yes' about seeking another term, and Rick Scott told the same outlet that Trump has not floated a rival and that he himself does not plan to challenge Thune again. Senators tend to protect a leader who kept their seats and punish one only after losses, so the Republican side of this question turns almost entirely on control.

History

What happened the last times this came up?

The reference class is changes in Senate control since 1980. In seven of nine, the outgoing minority leader became majority leader: Howard Baker, Robert Byrd, Bob Dole, Tom Daschle, Harry Reid, Mitch McConnell and Schumer. The two exceptions were voluntary departures, not caucus defeats: Trent Lott stepped down in late 2002 after his remarks praising Strom Thurmond's segregationist campaign, and McConnell chose not to seek the post again in 2024, which is how Thune got it.

The closest analogue for Schumer is Nancy Pelosi in the House in 2019: a leader facing public opposition from newly elected members who won anyway once her party took the majority. The analogy breaks in two places. Senate leaders are chosen by secret ballot in the caucus, which makes defections cheaper than a public House floor vote. And Pelosi was not also weighing whether to face a primary at home; Schumer has not said whether he will seek a sixth term in 2028.

Statistics

Base rate, adjustments, the number.

Start with control. Our Senate forecast is now 66 percent for Democrats as of October 15, down from 67: Texas tightened and Iowa's October polls are split, while Kansas joined the Toss Ups and Roy Cooper leads comfortably in North Carolina. In the Democratic world, Schumer's base rate as the sitting leader is about seventy-eight percent (seven of nine). On October 12 we cut that to about sixty-nine percent because Democratic nominees in Michigan, Minnesota and Maine have said they will not vote for him and he has not said whether he will seek his own seat again in 2028. Axios reported on October 15 that he is "more than favored" to win the secret ballot to remain leader, so we restore a few points, to about seventy-two percent. Our calculation: 0.66 times 0.72 gives about 0.48 for Schumer, still well below the base rate because that rate applies only once his party has won.

In the Republican world (34 percent), Thune keeps the job about ninety-three percent of the time, since he has said he will run and no rival has emerged: by our calculation, 0.34 times 0.93 gives about 0.32. The rest of the Democratic branch, about 18 points, goes mostly to Schatz, then Van Hollen and Cortez Masto; the rest of the Republican branch goes mostly to Whip John Barrasso.

Between the lines

What people spent versus what they said, and what was left out.

Tone shift

Axios described Schumer on October 15 as on the cusp of reclaiming the majority leader title and "more than favored" to win the secret ballot to remain Democratic leader.

Reporting built on caucus sources this close to the election is a read of what senators expect, not what candidates pledged in primaries. It suggests the anti-Schumer pledges have not grown into an organized alternative.

Sequencing

Troy Jackson, one of the nominees pledged against Schumer, still leads Susan Collins narrowly in Maine, 49 to 47 in a Suffolk University poll reported October 14.

The same tide that makes Schumer likelier to lead a majority also makes it likelier that his critics win. Each pledged opponent who reaches the Senate raises the number of returning senators he needs.

Personnel move

Brian Schatz has locked up the votes to become Senate Democratic whip, the No. 2 post, when Dick Durbin retires.

The caucus has already chosen its next-in-line. That makes a leadership change less chaotic, and it makes Schatz the default successor if Schumer decides to step aside rather than fight.

Tone shift

Rick Scott said Trump has not floated a rival to Thune, and Scott himself said 'been there, done that' about challenging him again.

The most likely source of a Republican challenge is standing down in public, which makes a Thune loss to a rival unlikely unless the midterm result is very bad.

History vs the market vs our call

Our number after adjusting the base rate for what is different this time: 48%. It sits inside the historical interval.

Check our statistics yourself

Reference class: 7 of 9 (78%)
Exact 95% CI (Clopper-Pearson): 40.0 to 97.2%
Bayesian 95% credible (uniform prior): 44.4 to 93.3%
Binomial test of our 48%: p = 0.098

Our 48% sits inside the historical interval: the forecast is consistent with how cases like this have gone.

Reproduce in JASP (free, jasp-stats.org)

Download base-rate.csv (one row per case in the reference class, outcome 1 or 0) and open it in JASP.
Frequencies, then Binomial Test. Variable: outcome. Test value: 0.48. Tick Confidence interval. JASP reports the same p value and Clopper-Pearson interval shown here.
Frequencies, then Bayesian Binomial Test, with a Beta(1, 1) prior. The posterior 95% credible interval matches ours.

Reference class: Our calculation from Senate leadership records: Baker (1981), Byrd (1987), Dole (1995), Daschle (2001), Reid (2007), McConnell (2015) and Schumer (2021) moved up; the exceptions were Trent Lott stepping down before 2003 and McConnell retiring from leadership before 2025.

Base rate

78%

of changes in Senate control since 1980 in which the outgoing minority leader became majority leader[12][9][10]

Our calculation from Senate leadership records: Baker (1981), Byrd (1987), Dole (1995), Daschle (2001), Reid (2007), McConnell (2015) and Schumer (2021) moved up; the exceptions were Trent Lott stepping down before 2003 and McConnell retiring from leadership before 2025. (n = 9)

Closest historical parallels

Pelosi survives a rebellion after winning the House (2019)
Alike: A party leader publicly opposed by new members elected in a Democratic wave against Trump.
Outcome: Pelosi was elected Speaker after agreeing to term limits with her critics.
Where it breaks: Senate leaders are chosen in a secret caucus ballot, where defections cost less than on the House floor.
Lott steps aside (2002)
Alike: A leader whose party won the majority but whose position became untenable before the new Congress convened.
Outcome: Lott stepped down and Bill Frist became Majority Leader in January 2003.
Where it breaks: Lott fell over a specific controversy; Schumer's challenge is a broader generational and ideological one.
McConnell passes the torch to Thune (2024)
Alike: A long-serving leader handing off after his party won the majority.
Outcome: Thune beat Cornyn and Rick Scott in the conference vote.
Where it breaks: McConnell announced his departure months in advance; Schumer has not.

How it could play out

Every path we see, sized by probability. Paths where the frontrunner wins add up to 48%.

Democrats win and Schumer is reelected leader easily Yes35%
Democrats win a working majority and most pledged opponents either lose or accept a deal on the caucus vote.
Republicans hold and Thune stays No32%
Republicans keep 50 or more seats and Thune runs unopposed for leader.
Democrats win and a new leader takes over No18%
A narrow majority with several pledged opponents, or Schumer's own decision to step aside, opens the post to Schatz or another senator.
Democrats win and Schumer survives a contested caucus vote Yes13%
Several new senators vote against him in the secret ballot, but returning senators carry him.
Republicans hold but pick a new leader No2%
A poor result or a Trump-backed challenge pushes Thune out despite a hold.

What would change our number

↓

Our Senate forecast moves back toward Republicans by ten points

-7 points for Schumer, +9 for Thune, likely flipping the frontrunner

↓

A sitting Democratic senator announces a challenge to Schumer

-10 points for Schumer

↑

A pledged opponent such as Troy Jackson softens the pledge before Election Day

+2 points for Schumer

↑

Democrats win 53 or more seats

Schumer rises toward 70 percent as critics lose leverage

How this question resolves

Resolves to the senator serving as Senate Majority Leader, the elected floor leader of the party that organizes the Senate, when the 120th Congress convenes on January 3, 2027. The majority party is the one whose conference controls the chamber, counting independents by the conference they join and the Vice President's tiebreak in a 50-50 Senate. Later changes in leadership do not count.

Closes: January 31, 2027. Judged by: Senate party conference leadership elections and the Senate's official leadership roster, as reported by the Associated Press

Questions people ask

Who will be Senate Majority Leader in 2027?

As of October 15, 2026, Chuck Schumer is the most likely Senate Majority Leader in January 2027, at 48 percent in our forecast, ahead of John Thune at 32 percent. If Democrats win the Senate, which our desk puts at 66 percent, Schumer is favored to become Majority Leader again despite opposition from several nominees. If Republicans hold it, Thune is very likely to keep the job.

Will Chuck Schumer remain Democratic leader after the 2026 midterms?

Probably, but it is less certain than usual. Axios reported in October 2026 that Schumer is more than favored to win the caucus secret ballot to remain leader. But Democratic nominees in Michigan, Minnesota and Maine have said they will not vote for him, and Newsweek's August list of opponents adds an Illinois nominee and Sen. Elissa Slotkin. We give him about a 72 percent chance of staying leader if Democrats win.

Who could replace Chuck Schumer as Senate Democratic leader?

The most often mentioned names are Brian Schatz of Hawaii, who has locked up the votes to become Democratic whip and is seen as Schumer's preferred successor, and Chris Van Hollen of Maryland, the name most floated by progressives. Catherine Cortez Masto of Nevada, Cory Booker and Chris Murphy have also been mentioned.

Will John Thune run for Republican leader again?

Yes. Asked in September 2026 whether he would run again for leader after the midterms, Thune said 'the assumption is yes,' and a GOP aide confirmed he will seek to keep the post. No viable rival has emerged, and Sen. Rick Scott, who challenged him in 2024, says he will not run again.

Sources

Every source is dated on or before the October 15, 2026 evidence cutoff. Nothing published later was used.

[1]'The assumption is yes,' Thune says of another leadership run. Roll Call, Sep 24, 2026.
“the South Dakota Republican said Thursday afternoon when asked if he would run again for leader in November”
[2]'The assumption is yes,' Thune says of another leadership run. Roll Call, Sep 24, 2026.
“said that Trump has not floated a rival to Thune for after the midterms and that he himself was not planning on challenging him again”
[3]'The assumption is yes,' Thune says of another leadership run. Roll Call, Sep 24, 2026.
“when he defeated Texas Sen. John Cornyn and Florida Sen. Rick Scott to succeed Mitch McConnell of Kentucky”
[4]Questions about Schumer's future grow as Democratic candidates call for change. The Hill via Yahoo News, Aug 17, 2026.
“Even so, Senate Democratic insiders say Schumer, who is 75, is likely to remain as Democratic leader.”
[5]Questions about Schumer's future grow as Democratic candidates call for change. The Hill via Yahoo News, Aug 17, 2026.
“Abdul El-Sayed in Michigan, Peggy Flanagan in Minnesota and Troy Jackson in Maine, who are all running as Democratic Senate nominees”
[6]Questions about Schumer's future grow as Democratic candidates call for change. The Hill via Yahoo News, Aug 17, 2026.
“who has locked up the votes to become Senate Democratic whip, as a candidate to succeed Schumer one day”
[7]Chuck Schumer's Future in Doubt: Full List of Democrats Rallying Against Him. Newsweek, Aug 12, 2026.
“Van Hollen is the name most often floated by progressives and Democrats aligned with the party's primary voters”
[8]Chuck Schumer's Future in Doubt: Full List of Democrats Rallying Against Him. Newsweek, Aug 12, 2026.
“He has not said publicly whether he will seek a sixth term in 2028.”
[9]Chuck Schumer. Wikipedia, Sep 26, 2026.
“he has led the Senate Democratic Caucus since 2017 and served as Senate majority leader from 2021 to 2025”
[10]About Leader Thune. Office of the Senate Republican Leader, Sep 26, 2026.
“He also serves as the Senate Majority Leader, and has previously served as the Senate Republican Whip”
[11]Questions about Schumer's future grow as Democratic candidates call for change. The Hill via Yahoo News, Aug 17, 2026.
“growing buzz around Sen. Catherine Cortez Masto (Nev.), a more centrist Democrat”
[12]Trent Lott. Wikipedia, Sep 26, 2026.
“In 2003, he stepped down from the position after controversy due to his praising of Strom Thurmond”
[13]Chuck Schumer's Future in Doubt: Full List of Democrats Rallying Against Him. Newsweek, Aug 12, 2026.
“while Schatz is viewed as Schumer's preferred successor”
[14]About Chris. Office of Senator Chris Van Hollen, Sep 26, 2026.
“Elected to the United States Senate by the people of Maryland in November 2016”
[15]About John Barrasso. Office of Senator John Barrasso, Sep 26, 2026.
“He serves as the Senate Majority Whip, the number two position in Senate Republican leadership.”
[16]Democrats' chances of winning Senate shift on Nate Silver forecast. Newsweek, Sep 15, 2026.
“gave the party a 58.6 percent chance of winning the chamber on September 14, up from 50.6 percent on September 6.”
[17]The Fight for the Senate Is a Toss Up. Political Wire, Sep 23, 2026.
“is Democrats netting between one and five seats; they must net four to win back the Senate.”
[18]What history tells us about the 2026 midterm elections. Brookings, Aug 28, 2025.
“Republicans are defending 22 seats next year compared to just 13 for Democrats”
[19]Schumer's final fight. Political Wire (quoting Axios), Oct 15, 2026.
“is more than favored to win a secret ballot to remain Democratic leader”
[20]Troy Jackson narrowly leads in Maine Senate race. Political Wire, Oct 14, 2026.
“finds Troy Jackson (D) leading Susan Collins (R) in the U.S. Senate race, 49% to 47%.”
[21]Five Senate races are now Toss-ups. Political Wire (quoting Sabato's Crystal Ball), Oct 14, 2026.
“Rating changes this week leave us with five Senate Toss-ups, all in Republican-held seats.”

Version history and integrity

Published forecasts are never edited. When the evidence changes we publish a new version beside the old one, each locked with a sha256 hash of its full contents. When this question resolves it is scored in public on our track record.

Version	Cutoff	Forecast	Lock hash
v3	Oct 15, 2026	Chuck Schumer 48% frontrunner	c02863dc4626ac28442b3386ada4542c57ca994df6a0818c7118756505abdda2
v2	Oct 12, 2026	Chuck Schumer 46% frontrunner	0ee835a2955335ba9ae369e9b3bb2edee19b863bb771ffa59671feece0a287f5
v1	Sep 26, 2026	Chuck Schumer 40% frontrunner	840e1dc33eb441bf4a82efd319f99f19fae8ed0daa0d661c396b1c7975af1914

Download every forecast: JSON or CSV (CC BY 4.0). Public sources only. Analysis, not investment or legal advice.

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