What to watch: Eight Democrats are looking to unseat Governor Scott Walker, a Republican who is seeking a third term. The front-runner in the crowded Democratic field is Tony Evers, the state superintendent, who led Mr. Walker by as many as 13 points in one recent poll. Read more

At the federal level, five Republicans are hoping to unseat Senator Tammy Baldwin, a first-term Democratic incumbent running in a state Mr. Trump narrowly won in 2016. Two front-runners on the Republican side — State Senator Leah Vukmir and businessman Kevin Nicholson — are locked in a bitter battle, most recently over a familiar theme: who supports Mr. Trump more.

Two Republican-held House districts are considered competitive here, including one long occupied by Representative Paul Ryan, the House speaker who is retiring. Two Democrats, including union organizer Randy Bryce, and five Republicans are running for Mr. Ryan’s seat in the First Congressional District, which has been held by a Republican in more than two decades. In the Sixth District, which Mr. Trump won by 17 points in 2016, Democrats are hoping to oust Representative Glenn Grothman, a two-term Republican incumbent.

— SYDNEY EMBER

Read more about today’s most important races.