In our calculation, each number is the chance a candidate runs times the chance they win if they do. Harris: about 45 percent to run, given her public hesitancy and CNN's reporting that her former aides have been given no hint of her plans, times about 27 percent to win if she runs (the 50 percent poll-leader base rate, cut for being a losing former nominee and for a market that prices her at 7 cents). That gives about 12 percent. Newsom runs only if Harris does not, so about 52 percent to run, times about 33 percent to win, gives about 17 percent.
Ocasio-Cortez: about 45 percent to choose the presidential race over the Senate, times about 30 percent to win, gives about 14 percent. Ossoff: about 30 percent to reverse his pledge, times about 35 percent, gives about 10 percent. Buttigieg, Shapiro and Beshear are likelier to run but start lower, at 8, 7 and 5 percent. That leaves 27 percent for everyone else, more than any single named candidate, which is why we call the field wide open. Kalshi has Ossoff 17, Ocasio-Cortez 16, Newsom 13, Harris 7 and Buttigieg 5, so our field is similar in shape but lower on Ossoff and higher on Harris.
Why our frontrunner sits far below the 4 of 8 base rate: that rate is the win rate of the early poll leader in an open Democratic contest, conditional on running. The poll leader today is Harris, not Newsom, and our 12 percent for her equals roughly half of a 4 of 8 rate (cut for her status as a losing former nominee) times our estimate that she runs, as shown above. No candidate in this field is a declared frontrunner, so no single name should carry the reference class rate; the 27 percent for the rest of the field reflects that. The October 12 check found no announcement, committee filing or withdrawal by any named contender since September 26, so the numbers hold. The polling averages and market prices cited in this version are as of late September; we could not open the live pages on October 12.