Trader consensus strongly favors zero Democratic Senate incumbents losing their primaries (81% implied probability), driven by incumbency advantages and weak challenger fields in remaining contests. No upsets have occurred in primaries held to date, including Bob Casey's easy win in Pennsylvania on April 23 amid minimal opposition, and safe advances for incumbents like Gary Peters in Michigan and Ron Wyden in Oregon on May 21. Upcoming June 4 primaries feature Jon Tester in Montana facing low-profile challengers, alongside unopposed paths for Cory Booker in New Jersey and Martin Heinrich in New Mexico. Historical base rates show Senate incumbents rarely lose primaries, with traders pricing slim odds for even one loss (10%) absent major scandals or fundraising surges.
Experimental AI-generated summary referencing Polymarket data · UpdatedHow many Democratic Senate Incumbents will not win their Primary?
How many Democratic Senate Incumbents will not win their Primary?
0 71%
1 20.0%
3 4.1%
4 2.5%
0
81%
1
10%
2
15%
3
4%
4
3%
>4
2%
0 71%
1 20.0%
3 4.1%
4 2.5%
0
81%
1
10%
2
15%
3
4%
4
3%
>4
2%
This market will resolve according to the number of Democratic Senate incumbents who do not win their nominating election to move on to the general election as a result of the 2026 midterm primary elections.
An incumbent will be considered not to have won their election if they are not declared the winner of the election they sought, including if they withdraw, suspend, or otherwise leave the race at any point after officially registering as a candidate, regardless of the reason. Incumbents who do not officially register as candidates for reelection will not be considered.
This market will resolve based on the results of all Senate nominating elections, including party primaries, top-two or jungle primaries, and primaries for special elections, that are scheduled to occur between March 1 and September 30, 2026. If a required runoff for any such election or a subsequent qualifying round in a non-partisan primary system could change the market’s outcome, the market will remain open until that contest is conclusively called by this market’s resolution sources.
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time of their nominating election. A candidate without a ballot-listed affiliation to either the Democratic or Republican parties will be considered a member of one of these parties based on the party with which they most recently expressed their intent to caucus prior to the conclusion of the relevant nominating election.
The resolution source for this market will be the Associated Press, Fox News, and NBC. This market will resolve once all three sources have conclusively called all relevant nominating elections. If all three sources do not achieve consensus in calling the relevant races for this market, it will resolve based on official state certification of the nominating election results.
Market Opened: Jan 14, 2026, 2:52 PM ET
Resolver
0x2F5e3684c...Resolver
0x2F5e3684c...Trader consensus strongly favors zero Democratic Senate incumbents losing their primaries (81% implied probability), driven by incumbency advantages and weak challenger fields in remaining contests. No upsets have occurred in primaries held to date, including Bob Casey's easy win in Pennsylvania on April 23 amid minimal opposition, and safe advances for incumbents like Gary Peters in Michigan and Ron Wyden in Oregon on May 21. Upcoming June 4 primaries feature Jon Tester in Montana facing low-profile challengers, alongside unopposed paths for Cory Booker in New Jersey and Martin Heinrich in New Mexico. Historical base rates show Senate incumbents rarely lose primaries, with traders pricing slim odds for even one loss (10%) absent major scandals or fundraising surges.
Experimental AI-generated summary referencing Polymarket data · Updated
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