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

Voters in six US states are casting primary ballots that will set the battle lines for November’s midterm elections.

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 primary days of the year, with voting under way 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. Democrats are hoping to win majorities in both chambers and wrest control back from the Republicans.

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.

One of the most closely watched races is in Iowa, a rural state that 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 US 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.

Much attention is focused on New Jersey’s