Primary elections in seven states Tuesday will set the stage for U.S. House and Senate races this fall, with many contests shaped by political fissures in both major parties and the lingering shadow of former President Donald Trump.

With control of Congress in play, a string of Republican House incumbents are contending with challenges from the political right, and some rivals are embracing Trump’s baseless claims of election fraud in his 2020 loss to President Joe Biden.

No incumbent governors or senators appear to be in imminent danger. In Iowa, several Democrats are jockeying for the chance to take on seven-term Republican Sen. Chuck Grassley, with the campaign showcasing the breach between the Democratic Party’s progressive and establishment wings.

Former Trump Cabinet member Ryan Zinke is seeking the GOP nomination in a newly created House district in Montana.

What to watch in Tuesday’s primaries in California:

CALIFORNIA

California is a Democratic fortress where the party holds every statewide office and its voters outnumber registered Republicans by nearly 2-to-1. Gov. Gavin Newsom and U.S. Sen. Alex Padilla face little-known competitors.

But Republicans retain pockets of strength in some U.S. House districts that are expected to be among the most competitive races in the country.

In a heavily Democratic district in the state’s Central Valley farm belt, Republican U.S. Rep. David Valadao is seeing blowback for his vote to impeach Trump over the Jan. 6 U.S. Capitol insurrection. Republican Chris Mathys has made Valadao’s vote a centerpiece in his campaign to oust him.

In a Democratic-leaning district north of Los Angeles, several Democrats are hoping to take on Republican Rep. Mike Garcia, who is expected to advance to November with one of the Democrats as the top two finishers in the race. Garcia rejected electoral votes from Arizona and Pennsylvania being cast for Biden and opposed Trump’s impeachment after the Capitol insurrection.

The crowded Los Angeles mayor’s race is shaping up to be a fight between Rick Caruso, a pro-business billionaire Republican-turned-Democrat who sits on the board of the Ronald Reagan Presidential Foundation, and Democratic U.S. Rep. Karen Bass, who was on Biden’s shortlist for vice president. If no candidate clears 50%, the top two finishers advance to a November runoff.

In another closely watched election, San Francisco voters are considering whether to recall District Attorney Chesa Boudin, a progressive Democrat who critics say has failed to prosecute repeat offenders, amid widespread frustration with crime and homelessness.