Incumbent Republican Mary Miller faces Democrat Jennifer Todd in the solidly Republican IL-15 district, which carries an R+20 Partisan Voter Index and saw Donald Trump win by roughly 22 points in 2024. Trader probabilities cluster around a 25-35 point Republican margin of victory, reflecting the district’s rural conservative base across central Illinois counties and Miller’s strong primary performance. Recent campaign activity has centered on standard midterm issues such as immigration, economic conditions, and federal policy priorities, with limited polling or major spending surges reported to date. Factors that could widen or narrow the margin include shifts in national political sentiment, differential turnout between rural Republican strongholds and suburban or college-town areas, and any late-cycle endorsements or advertising that alter voter enthusiasm in the final weeks before the November 3 election.