What to watch: The biggest race in Kansas is for governor, a job held by Jeff Colyer since Sam Brownback resigned to accept an ambassadorship. Mr. Colyer is running against Secretary of State Kris W. Kobach, the face of President Trump’s voter fraud panel, in the Republican primary. In a dynamic that has become very familiar this year, they are fighting to be seen as the most loyal and effective ally of the president. Read more

Also running are three Democrats: Carl Brewer, a former mayor of Wichita; Laura Kelly, a state senator; and Josh Svaty, a farmer and former state agriculture secretary. Any of them would face long odds in November in a state as conservative as Kansas. But some Democrats think that if Mr. Kobach wins the Republican nomination, it could give them an opening among voters who see him as too extreme.

There are also competitive races in two Republican-held congressional districts that Democrats hope to flip in November. Seven Republicans are vying for the nomination in the Second District, where Representative Lynn Jenkins is retiring; the winner will face Paul Davis, a Democrat who won the district during his unsuccessful run for governor in 2014. And in the Third District, which includes Democratic-leaning Kansas City and Overland Park, six Democrats are vying to challenge Representative Kevin Yoder.

— MAGGIE ASTOR

Read more about today’s most important races.