The general election for a race that could determine the Senate majority begins right after Montana voters lock in their nominees in Tuesday’s primaries.

The center of the political storm in Montana is the U.S. Senate race, in which Democrat Jon Tester is running for reelection. Republican leaders including Sen. Steve Daines, chairman of the National Republican Senatorial committee, are supporting Tim Sheehy for the GOP nomination. Sheehy, a retired Navy SEAL who has the personal wealth to help pay for an expensive challenge to Tester, faces two other candidates on the ballot.

Rep. Matt Rosendale’s attempt to join the race was quickly rebuffed when former President Donald Trump endorsed Sheehy the day that Rosendale announced he was running for Senate, too. Rosendale dropped out of the race less than a week later, announcing his intent to run for reelection instead. At that point, however, Republicans had already lined up to run for his open House seat. Now, Rosendale isn’t running for office in 2024 at all.

State Auditor Troy Downing is among the candidates in a crowded primary to replace Rosendale, as are former Rep. Denny Rehberg and several others. Meanwhile, the other member of Montana’s congressional delegation, Rep. Ryan Zinke, is running for reelection, as is Gov. Greg Gianforte.

Tester is a top target for Republicans, one of two Democrats running for reelection in a state that Trump won in 2020. Rosendale failed to oust Tester in the 2018 race, and Republicans are hoping that Sheehy will be more successful.

Rosendale’s open seat might mean a major political comeback for Rehberg, or a launching pad for another candidate in the crowded field. Daines served in the at-large congressional seat before making the leap to the Senate. And Gianforte, who won a House seat in a contentious 2017 special election, is now governor.

Here’s a look at what to expect on Tuesday:

PRIMARY DAY

The primary will be held Tuesday. Polls close at 10 p.m. ET, or 8 p.m. local time.

WHAT’S ON THE BALLOT

The Associated Press will provide results for and determine winners in 72 races, including the presidential primaries. Trump and President Joe Biden, a Democrat, are the only candidates on their respective ballots, but voters have the option to select “no preference” or write in a candidate in both races.

The AP is also tabulating results for the Republican and Democratic primaries for the U.S. Senate race. Tester appears on the Democratic ballot alongside Michael Hummert, who had not filed any campaign fundraising as of the latest deadline. Tester has $11.8 million on hand and has spent $26 million this cycle as of latest filing.

Voters will also select nominees for governor and lieutenant governor, who run as a team, as one ballot option.

Other statewide offices including secretary of state and attorney general appear on the ballot as well as state legislative primaries and judicial races.

WHO GETS TO VOTE

Montana has an open primary system, which means any registered voter may participate in any party’s primary.

DELEGATE ALLOCATION RULES

Montana’s 20 pledged Democratic delegates are allocated according to the national party’s standard rules. Five at-large delegates are allocated in proportion to the statewide vote, as are three PLEO delegates, or “party leaders and elected officials.” The state’s two congressional districts have a combined 12 delegates at stake, which are allocated in proportion to the vote results in each district. Candidates must receive at least 15% of the statewide vote to qualify for any statewide delegates, and 15% of the vote in a congressional district to qualify for delegates in that district.

In the Republican primary, 31 delegates are unbound to a presidential candidate.

DECISION NOTES

Sheehy has never appeared on a ballot for statewide office, but he has a major financial advantage in the Republican primary for U.S. Senate. He has already spent $8.3 million as of a May 15 filing and had an additional $2.2 million in the bank. Two other candidates on the ballot have not come close to keeping up with Sheehy’s fundraising or spending.

Gianforte is running for another term as governor alongside Lt. Gov. Kristen Juras. He faces a challenge from the right by state Rep. Tanner Smith, who represents part of Flathead County in the state House. Smith’s running mate, Randy Pinocci, represents District 1 on the Public Service Commission, which covers much of the eastern portion of the state.

After decennial redistricting, Montana’s at-large congressional district was split in two. The first district covers the western portion of the state, running along the Idaho border. Most of the district favors Republicans, though there are Democratic-leaning pockets around a handful of cities, including Bozeman, Missoula and Butte. For that reason, the 1st District has become a target for Democrats. In 2022, Zinke won the general election by just about 3 percentage points over Democratic nominee Monica Tranel, who’s running uncontested for the nomination in 2024.

The 2nd District falls in the eastern portion of the state, stretching from Helena to the North Dakota border and is even friendlier to Republicans than the 1st District. Rehberg, Downing and Superintendent of Public Instruction Elsie Arntzen have appeared on a statewide ballot before, making them familiar names to many voters. According to data from AdImpact, Downing has a significant advantage over his competitors in ad spending on the race.

Ken Bogner, president pro tempore of the state senate, is also running for the open 2nd District seat. Bogner is from Miles City in Custer County. A number of other candidates also appear on the ballot but have lagged far behind in campaign fundraising.

The AP does not make projections and will declare a winner only when it’s determined there is no scenario that would allow the trailing candidates to close the gap. If a race has not been called, the AP will continue to cover any newsworthy developments, such as candidate concessions or declarations of victory. In doing so, the AP will make clear that it has not yet declared a winner and explain why.

Montana elections automatically go to a recount in the event of a tied vote. Candidates may request a recount if the margin of the race is less than a half a percentage point.

WHAT DO TURNOUT AND ADVANCE VOTE LOOK LIKE

As of May 22, there were 752,395 registered voters in Montana. Montana voters do not register with a political party.

In the 2020 presidential election, turnout was 22% of registered voters in the Democratic primary and 31% in the Republican primary.

In the June 2022 primary, about 87% of votes were cast before Election Day.

As of May 28, a total of 448,022 ballots had been sent to voters, and 136,979 had been returned.

HOW LONG DOES VOTE-COUNTING USUALLY TAKE?

In the 2022 primary election, the AP first reported results at 10:06p.m. ET, or six minutes after polls closed. The election night tabulation ended at 6:02 a.m. ET with about 93% of total votes counted.

ARE WE THERE YET?

As of Tuesday, there will be 41 days until the Republican National Convention in Milwaukee, 76 days until the Democratic National Convention in Chicago and 154 days until the November general election.