IA-03 House winner? — In 2026

Iowa's 3rd Congressional District, currently a competitive seat, is up for election in the 2026 midterms on November 3, 2026. Prediction markets are pricing both the partisan outcome and specific candidates who could hold the seat when the new Congress is sworn in for the term beginning in 2027. On the party question, Polymarket implies a 75.5% chance that a Democrat wins IA-03, versus 23.5% for a Republican, making the Democratic Party the clear favourite by roughly 52 points. Kalshi frames the market around named candidates rather than parties: Sarah Trone Garriott, a Democrat, sits at 74.0%, while Republican incumbent-side name Zach Nunn trades at 31.0%. Those candidate-level prices are broadly consistent with Polymarket's partisan read, suggesting traders view Trone Garriott as carrying essentially the entire Democratic probability, with Nunn accounting for most of the Republican side. Because each outcome is quoted on only one venue, there is no direct cross-platform spread to arbitrage on identical contracts, and the reported spread on each line is 0.0 points. The cross-platform takeaway is that Kalshi and Polymarket agree directionally: IA-03 is currently priced as a Democratic-leaning race, with Trone Garriott as the specific candidate carrying that lean.