Incumbent Democrat Jim Costa, who has represented California’s 21st congressional district since 2005 and won re-election in 2024 with 52.6% of the vote, advanced from the June 2026 top-two primary alongside Republican Kyle Kirkland. Forecasters rate the Central Valley seat Likely or Solid Democratic, reflecting its partisan composition, Costa’s established record on agriculture and water issues, and limited Republican infrastructure in the district. The current trader consensus aligns with these structural advantages and the absence of major recent developments, such as scandals or redistricting shifts, that would alter the balance. A significant national Republican surge, unexpected primary dynamics in future cycles, or late-cycle events could narrow the margin, though such outcomes remain low-probability given historical patterns in similar seats.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · UpdatedCA-21 House Election Winner
CA-21 House Election Winner
$24,749 Vol.
$24,749 Vol.
Nov 2, 2026
Democratic Party
92%
Republican Party
9%
$24,749 Vol.
$24,749 Vol.
Nov 2, 2026
Democratic Party
$14,407 Vol.
92%
Republican Party
$10,342 Vol.
9%
This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026.
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).Incumbent Democrat Jim Costa, who has represented California’s 21st congressional district since 2005 and won re-election in 2024 with 52.6% of the vote, advanced from the June 2026 top-two primary alongside Republican Kyle Kirkland. Forecasters rate the Central Valley seat Likely or Solid Democratic, reflecting its partisan composition, Costa’s established record on agriculture and water issues, and limited Republican infrastructure in the district. The current trader consensus aligns with these structural advantages and the absence of major recent developments, such as scandals or redistricting shifts, that would alter the balance. A significant national Republican surge, unexpected primary dynamics in future cycles, or late-cycle events could narrow the margin, though such outcomes remain low-probability given historical patterns in similar seats.
This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026.
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).
Market Opened: Jan 28, 2026, 12:08 AM ET
Volume
$24,749End Date
Nov 3, 2026Market Opened
Jan 28, 2026, 12:08 AM ETResolver
0x2F5e3684c...This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026.
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).Incumbent Democrat Jim Costa, who has represented California’s 21st congressional district since 2005 and won re-election in 2024 with 52.6% of the vote, advanced from the June 2026 top-two primary alongside Republican Kyle Kirkland. Forecasters rate the Central Valley seat Likely or Solid Democratic, reflecting its partisan composition, Costa’s established record on agriculture and water issues, and limited Republican infrastructure in the district. The current trader consensus aligns with these structural advantages and the absence of major recent developments, such as scandals or redistricting shifts, that would alter the balance. A significant national Republican surge, unexpected primary dynamics in future cycles, or late-cycle events could narrow the margin, though such outcomes remain low-probability given historical patterns in similar seats.
This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026.
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).
A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat 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 at the time all of the House elections are conclusively called by this market's resolution sources.
This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).
Volume
$24,749End Date
Nov 3, 2026Market Opened
Jan 28, 2026, 12:08 AM ETResolver
0x2F5e3684c...Incumbent Democrat Jim Costa, who has represented California’s 21st congressional district since 2005 and won re-election in 2024 with 52.6% of the vote, advanced from the June 2026 top-two primary alongside Republican Kyle Kirkland. Forecasters rate the Central Valley seat Likely or Solid Democratic, reflecting its partisan composition, Costa’s established record on agriculture and water issues, and limited Republican infrastructure in the district. The current trader consensus aligns with these structural advantages and the absence of major recent developments, such as scandals or redistricting shifts, that would alter the balance. A significant national Republican surge, unexpected primary dynamics in future cycles, or late-cycle events could narrow the margin, though such outcomes remain low-probability given historical patterns in similar seats.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · Updated
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