Millions of voters across the country are heading to the polls today in crucial primaries in a slew of key gubernatorial, Senate and House races.

Here’s a quick rundown of what we’re watching:

California
Voters are casting ballots on who should lead the nation’s most populous state (and the world’s fourth largest economy), where there is no clear leader among candidates vying to advance in the race to succeed term-limited Democratic governor Gavin Newsom. The race for Los Angeles mayor is also on the ballot, along with a series of high-stakes US House contests in the state’s newly redrawn congressional districts – which are set to play an outsized and potentially decisive role in the battle for power in Washington in November’s midterm elections. My colleague Lauren Gambino has more:

Iowa
Per my colleague Chris Stein, with Trump’s approval ratings deep underwater, gas prices high and historical political trends favoring the party out of power, Democrats this year are considering a comeback in Iowa, putting the state at the center of their campaigns to win back control of both the US House and the Senate. That effort for a “once-in-a-generation” breakthrough in the GOP-dominated state is being led by pro-hunting Democrat Rob Sand, who is running for governor. Chris wrote about him below. Democrats also believe they have a shot at winning three of the state’s US House seats and a competitive chance at securing a US Senate seat, where the GOP frontrunner recently called Trump’s war on Iran a “political liability”.

New Jersey
One of this year’s most closely watched House midterms will take place in the battleground district currently represented by now-infamous Republican Tom Kean Jr, who has drawn public scrutiny and concern after missing more than 100 House votes due to an undisclosed illness. Voters are deciding which Democrat will run against him in November – and the seat is a must-win for the party. The frontrunner, veteran army trauma surgeon and political newcomer Adam Hamawy, has secured endorsements from the likes of Bernie Sanders, Alexandria Ocasio-Cortez and Ilhan Omar. My colleague Joseph Gedeon has more:

New Mexico
Contests in the state include primaries for congressional seats, a US Senate seat and a long list of statewide offices, but the governor’s race is the main event. Deb Haaland, who was Joe Biden’s interior secretary, is running for the Democratic nomination, which could put her on a historic path for Native American leaders.

Montana
In Montana, a five-way Democratic fight is under way for the retiring Republican senator’s seat. Independent Seth Bodnar, former president of the University of Montana, is outraising them all at the moment but they’re refusing to step aside, Politico reports this morning.

South Dakota
The race is on for state governor, Sioux Falls mayor, a US Senate and House seat, a Republican primary for local lawmakers. The incumbent GOP governor Larry Rhoden faces three primary challengers in his first run for a full term. He stepped up into the role from the lieutenant governorship when the former governor, the since-ousted Kristi Noem, left to lead the Department of Homeland Security.

The Associated Press contributed reporting