Indiana State Senate District 25 covers all of Madison County and a portion of Hamilton County, anchored by the city of Anderson (population roughly 54,000). The district leans solidly Republican. In 2022, incumbent Mike Gaskill won with 64.1% over Democrat Tamie Dixon-Tatum's 35.9%.
What makes SD-25 distinctive in the 2026 cycle is not its competitiveness -- the seat is safe Republican territory -- but the convergence of three separate threads: Trump's endorsement of the incumbent as a reward for supporting redistricting, a party-discipline fight over a challenger declared "not in good standing," and a veteran Democratic candidate making her third consecutive run for the seat.
Gaskill is not merely a senator seeking reelection. He is the man who carried Trump's water on redistricting. He served as the Senate sponsor of HB 1032, the Trump-backed congressional redistricting bill, and used his Elections Committee to advance it to the floor. The bill went down 31-19. In March 2026, Trump endorsed Gaskill as one of 11 Republican senators who supported redistricting, calling them "MAGA WARRIORS."
Katherine Callahan's candidacy is less a conventional primary challenge than a case study in how Indiana's Republican Party disciplines its own. In February 2026, former Madison County Republican Party chairman Russ Willis filed a complaint against Callahan. The Fifth District determined Callahan is "not in good standing" with the party. The penalties include being barred from Republican party events and losing access to the party's proprietary voter database. Against a Trump-endorsed incumbent with a campaign war chest, committee chairmanship, and full party backing, Callahan faces essentially insurmountable odds.
Tamie Dixon-Tatum is nothing if not persistent. This is her third consecutive campaign for SD-25 and her fifth overall run for office since 2018. She holds a B.A. in Telecommunications, a Master's in Public Affairs, and a Master's in Legal Studies, and serves as Director of the City of Anderson's Human Relations Department. She has spearheaded the Ollie H. Dixon Back-To-School Picnic and Parade for nearly 25 years.
Todd Shelton offers a different kind of Democratic candidacy -- one built on the manufacturing economy that once defined Madison County. A former GM production worker and UAW member, disabled Army veteran, and current IUPUI senior lecturer, his platform emphasizes economic stability for working families. In a district where Anderson's post-industrial economy remains the defining reality, the choice between these two Democrats reflects a broader debate about whether to lean into identity-based advocacy or economic populism in hostile terrain.