The solidly Democratic partisan lean of Illinois’s fourth congressional district, rated D+17 on the Cook Partisan Voter Index and historically delivering 30-plus point margins for Democratic House candidates, anchors trader consensus behind the Democratic nominee. Incumbent Representative Jesús “Chuy” García retired in November 2025 after the filing deadline, clearing the path for his chief of staff, Patty Garcia, who advanced unopposed through the March 17, 2026 Democratic primary. The Republican nominee, Lupe Castillo, likewise faced no primary opposition and enters the November 3 general election without visible campaign infrastructure or recent precedent for competitive performance. Forecasters across multiple outlets continue to classify the race as Solid or Safe Democratic. A major scandal, health event, or unusually strong national Republican wave could theoretically narrow the margin, though structural and organizational advantages remain formidable barriers to an upset.
Experimental AI-generated summary referencing Polymarket data. This is not trading advice and plays no role in how this market resolves. · UpdatedIL-04 House Election Winner
$46,392 Vol.
$46,392 Vol.
Democratic Party
96%
Republican Party
4%
$46,392 Vol.
$46,392 Vol.
Democratic Party
96%
Republican Party
4%
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, 11:08 AM ET
Resolver
0x2F5e3684c...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/).
Resolver
0x2F5e3684c...The solidly Democratic partisan lean of Illinois’s fourth congressional district, rated D+17 on the Cook Partisan Voter Index and historically delivering 30-plus point margins for Democratic House candidates, anchors trader consensus behind the Democratic nominee. Incumbent Representative Jesús “Chuy” García retired in November 2025 after the filing deadline, clearing the path for his chief of staff, Patty Garcia, who advanced unopposed through the March 17, 2026 Democratic primary. The Republican nominee, Lupe Castillo, likewise faced no primary opposition and enters the November 3 general election without visible campaign infrastructure or recent precedent for competitive performance. Forecasters across multiple outlets continue to classify the race as Solid or Safe Democratic. A major scandal, health event, or unusually strong national Republican wave could theoretically narrow the margin, though structural and organizational advantages remain formidable barriers to an upset.
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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