The remaining three presidential candidates have only a few more races left in the primary season before they head to their respective party conventions in July. Likely Republican nominee Donald Trump has five states left, while Democrats Hillary Clinton and Bernie Sanders have six states and Washington DC left to reach the end of primary season.
On 7 June, Republican and Democratic voters will head to cast their votes in California, Montana, New Jersey, New Mexico and South Dakota. Democratic voters will also vote in North Dakota. While Trump has surpassed the necessary delegates needed to snatch the GOP nomination, Clinton is just 28 delegates short of clinching the Democratic nomination from Sanders.
IBTimes UK breaks down everything you need to know about the upcoming races. You can read part 2 of our primary preview here.
The primaries in the Golden State are by far the biggest haul of the night. There are 172 Republican delegates and 475 Democratic delegates at stake. Delegates will be awarded on a proportional system for Democrats and a winner-take-all system for Republicans.
Recent polls show the margin between Clinton and Sanders in California is narrowing. A CBS News/YouGov poll puts the former secretary of state ahead of the Vermont senator by just two percentage points. The same poll reveals Clinton leads Trump 48% to 33% among California voters in a general election matchup.
Polls will open at 7am PDT/3pm BST and close at 8pm PDT/4am BST. Voters registered with either party will only be able to vote for their party's candidates, while voters registered as Independents will be able to vote in either the Republican or Democratic primary.
There is a relatively small number of delegates at stake in Montana's primary, with 27 Republican delegates and 21 Democratic delegates up for grabs. Democratic delegates will be awarded on a proportional system, while Republican delegates will be awarded on a winner-take-all system.
There are no current polls coming out of Big Sky Country for either party. Polls will be open at 7am MDT/2pm BST and close at 8pm MDT/3am BST. The Montana primaries are open, which means that voters from any political affiliation can vote in either the Republican or Democratic races.
The Garden State will provide the second largest number of delegates for each party. There are 51 Republican delegates and 126 Democratic delegates available. Delegates will be awarded on a proportional system for Democrats and a winner-take-all system for Republicans.
Democratic frontrunner Clinton has a much larger lead against Sanders in New Jersey, with the new CBS News/YouGov poll putting her ahead 61% to 34%. Clinton also leads Trump in a general election matchup, 49% to 34%.
Polls will be open at 6am EDT/11am BST and will close at 8pm EDT/1am BST. As in California, voters registered with a particular party will only be able to vote in their respective primaries, but voters registered as Independents will be vote in either the Republican or Democratic primaries.