Will Republicans keep control of the U.S. Senate in the 2026 midterm elections?

Senate races are more candidate driven than House races, but a strong national tide pulls on all of them, and the early October polls suggest it is still pulling. Republican candidates in Ohio, Iowa and Michigan had already called for the Iran war to end, a sign they read the same mood in their own numbers. With incumbents such as Jon Husted and Dan Sullivan trailing in the New York Times/Siena polls, as Political Wire and Newsweek reported, Republican groups face pressure to spend on defense in states they expected to hold cheaply.

Party committees reveal their beliefs through triage. A Republican super PAC pulled $6.5 million in October reservations from North Carolina in September, conceding that race to free money elsewhere. That choice narrowed the Republican path to holding 50, and the October polls now put several of the places that money could go, Ohio, Alaska and Texas, in play at once.

The reference class is the midterms since 1946. By our count from the American Presidency Project table, the president's party lost four or more Senate seats in about half of them, nine or ten depending on how the 1974 result is scored, so a four-seat Democratic net gain is close to a coin flip in the raw record. Conditioning on unpopular presidents helps only a little: in roughly half or slightly more of the midterms since 1950 held under a president below half approval in late August, his party lost four or more Senate seats.

The closest analogue is 2006, when an unpopular war and a president in the high 30s cost Republicans six Senate seats and the majority, several of them in states the president had carried. The 2018 midterm was the warning that a House wave need not carry the Senate when the map runs through red states. That warning has weakened: the October polls show Democrats ahead in several states Trump carried in 2024, the 2006 pattern rather than the 2018 one.

Our September 26 number was 42 percent, which started from a base rate near one half and a slightly lower figure for unpopular-president midterms, then built the map seat by seat. Two pieces of October evidence move it. First, the New York Times/Siena wave released October 3, as Political Wire and Newsweek reported, showed Democrats ahead in Alaska, Texas and Ohio: Mary Peltola up seven in Alaska, outside that poll's margin of error, James Talarico up six in Texas and Sherrod Brown up three in Ohio, the last two inside their margins. Second, our down signpost, a lead of four or more for Talarico or Brown in quality October polls, has now been met: Political Wire reported a CNN poll with Brown up six and YouGov polls with Brown up four and Talarico up six.

Arithmetic: the signpost is worth 6 points, and the breadth of the Times/Siena wave, three Republican-held seats at once, is worth about 3 more, for 42 minus 9, or 33 (our calculation). We do not take the full amount twice, because the Texas Times/Siena poll was fielded mostly in late September and overlaps the signpost evidence. In Maine, Marist, UNH and AARP polls have Jackson ahead by three or four points and only the September Times/Siena poll had Collins ahead, which supports the move. The up signpost, Mike Rogers leading in Michigan, did not fire in any October poll we found. We stay above a pure polling read because most of these leads are inside the margin, Nebraska is close with an independent who will not commit to either party, and a 50-50 Senate still goes to Republicans through Vice President Vance.