The Senate race in Iowa is one of the most closely watched this year and the general election matchup is now set, with Democrats hoping for a gain.

Montana voters will select nominees in Tuesday’s state primary to replace two prominent Republican incumbents: U.S. Sen. Steve Daines and U.S. Rep. Ryan Zinke.

Republican U.S. Sen. Steve Daines of Montana has dropped his bid for reelection to a third term.