What to know about Tuesday’s primaries in California, New Jersey, Montana 

In the United States, voters in six states are participating in primary elections that will set up the final races in November’s critical midterm elections.

Tuesday is one of the busiest primaries days of the year, with voting underway in Iowa, Montana, New Mexico, New Jersey, South Dakota and California.

Candidates for no fewer than 74 seats in the US House of Representatives are on the ballot today, as voters decide who will progress to November’s general election.

Tuesday’s outcomes could shape the political landscape for the remainder of President Donald Trump’s second term, as frontrunners are decided for the midterms.

At stake is control over Congress. All seats in the House of Representatives, and roughly a third in the Senate, will be on November’s ballot.

Primaries generally allow voters to pick which Democratic and Republican candidates advance to a face-off, though there are variations on the format.

In California, for instance, most statewide primary races are nonpartisan, and the top-two vote-getters from any party move forward to November.

So what’s on the ballot this Tuesday? Here’s a breakdown of the races.

What to watch in Iowa

One of the most closely watched races is Iowa, a rural state which often opens presidential election seasons with its early races.

Iowa has long been dominated by the Republican Party, but Democrats believe there might be a chance to make the state’s Senate race competitive.

Republican Senator Joni Ernst is retiring, after more than a decade in office. That leaves an open seat in the Senate, without an incumbent to defend it.

To take control of the Senate in November, Democrats need to defend all their existing seats — and flip around four. Iowa offers a golden opportunity to gain ground.

Two main Democrats are racing to be their nominee for Ernst’s seat: State Representative Josh Turek and State Senator Zach Wahls. Turek is seen as more moderate than Wahls, and the Democratic establishment has largely rallied around him as the favourite for November.

The Republican Party’s best bet is expected to be US Representative Ashley Hinson, a Trump  loyalist who has repeatedly voted against limiting the president’s military powers.

If no candidate wins at least 35 percent of the primary vote, the Republican nominee will be chosen at the state party convention on June 13.

What to watch in New Jersey

A lot of attention on New Jersey’s primaries, too. As the 11th most populous state, it wields 12 seats in the House of Representatives.

One of its districts is represented by incumbent Congress member Tom Kean Jr. He is running unopposed in the Republican primary for New Jersey’s 7th congressional district.

Normally, incumbents are seen to have an advantage in November’s midterm races. The trouble is, Kean has missed more than 100 House votes and failed to attend public events in his district.

Kean issued a statement in April, explaining his absences as the result of a “personal medical issue”. But that explanation has been criticised as vague.

His seat is therefore vulnerable to a Democratic takeover in a state that can lean purple.

Democrats are hoping to gain control of the House of Representatives in November, where they currently hold a minority of 212 seats out of a total of 435.

Leading the Democratic primary race in the 7th district is Rebecca Bennett, a former Navy helicopter pilot.

But there are three other contenders for Kean’s seat: Michael Roth, a former Biden administration official; Tina Shah, a doctor; and Brian Varela, a businessman.

What to watch in Montana

The number seats each state gets in the House of Representatives reflects the number of residents they have.

Since 2022, Montana has had two House seats, a reflection of its relatively sparse population.

But every state, no matter the size, gets two senators. And unlike House members, who face election every two years, Senate members occupy their seats for a period of six years.

That makes the shakeup in Montana’s Senate race one to watch. The incumbent, Steve Daines, first won his seat in 2014, flipping it from Democratic control.

But days before the March deadline to appear on the primary ballot, Daines suddenly pulled out. Experts have speculated that the move was designed to clear the field for a Trump-endorsed Republican, Kurt Alme, who formerly served as a US attorney.

But five Democrats are racing in the party primary for a chance to compete for Daines’s vacant Senate seat in November.

There’s a complicating factor, though. One of the biggest candidates is not running in any primary at all.

Seth Bodnar, a Green Beret veteran and the former president of the University of Montana, has put himself forward as an independent. He therefore automatically progresses to November’s ballot, without having to face a primary.

Critics, however, point out that Bodnar has been using the Democratic fundraising platform ActBlue to raise money, according to media reports.

What to watch in New Mexico

Contenders here are competing for congressional seats, a US Senate seat and a long list of statewide offices, but the most coveted job is the one of the governor.

One of the most noteworthy gubernatorial campaigns has come from former Interior Secretary Deb Haaland, who is running for the Democratic nomination. Previously, she made history as the first Indigenous cabinet secretary in US history, serving under President Joe Biden.

Should she win the governor’s race in November, Haaland — a member of the Laguna Pueblo nation — would be the first Indigenous woman to be elected governor in the US.

What to watch in South Dakota

One of the least populated states, South Dakota only has a single House seat up for grabs.

After Representative Dusty Johnson decided to run for governor this year, his seat in the House was free.

Republicans are hoping to maintain control of that open seat, though. State Attorney General Marty Jackley is the most prominent candidate in the right-wing party’s primary. He has received Trump’s endorsement.

What to watch in California

California, a left-leaning state, is the big behemoth in Tuesday’s primaries.

As the state with the largest population, California is holding primaries for no fewer than 52 House races.

But many are unlikely to be competitive. Last year, California voted to redistrict to give Democrats an advantage, after Republican-led states did the same.

As a result, only California’s 22nd district is expected to be competitive. The area is currently in the midst of a heated three-way, nonpartisan primary, between Republican incumbent David Valadao, moderate Jasmeet Bains and progressive Randy Villegas.

California’s governor’s race is also expected to be competitive. With Governor Gavin Newsom facing his term limit, no fewer than 61 contenders are in the race to succeed him.

They include former cabinet secretary Xavier Becerra, progressive businessman Tom Steyer, Fox News personality Steve Hilton and Riverside County Sheriff Chad Bianco.

But some of the local races are also generating nationwide attention. In Los Angeles, reality TV star Spencer Pratt has launched a surprisingly competitive bid for mayor against incumbent Karen Bass, leveraging local outrage over wildfires and homelessness.