The two remaining competitive 2020 Democratic presidential candidates are once again on a collision course, with both now focusing on the potentially decisive primary in Michigan, Washington, Missouri, Mississippi, Idaho and North Dakota on Tuesday.

The contest will be the first time that Bernie Sanders and Joe Biden compete in a two-man race, after the former vice president swept through the South on Super Tuesday and amassed enough delegates to put his once-floundering campaign in the lead.

In the days before and after those key votes, Mr Biden enjoyed a coalescing of support around his bid with several prominent centrist candidates — including Pete Buttigieg, Amy Klobuchar and Mike Bloomberg — all suspending their campaign and announcing their backing of the now-front runner.

But Mr Sanders is far from finished in this race, and the results in Michigan could serve to either push his candidacy back into the race, or cement Mr Biden’s lead.

Here’s what you need to know.

What time do polls close?

There are six states voting, with the following closing times:

Michigan — 9pm ET

Washington — 11pm ET

Missouri — 6 pm ET

Mississippi — 8pm ET

Idaho — 11 pm ET

North Dakota — 8pm ET

How many delegates are at stake?

There are a total of 352 delegates up for grabs on “Big Tuesday”, which amounts to around a quarter of what was available one week ago on Super Tuesday.

By state, they offer:

Michigan — 125 delegates

Washington — 89 delegates

Missouri — 68 delegates

Mississippi — 36 delegates

Idaho — 20 delegates

North Dakota — 14 delegates

What state are we watching?

The largest prize of the night is Michigan, and Mr Sanders is hoping for a strong showing there in order to reverse the unexpected losses he saw on Super Tuesday.

In 2016, Mr Sanders pulled off an upset in the state against Hillary Clinton, relying on young voters who have so far not shown up in big numbers this election season — in spite of Mr Sanders’ promises that he would boost turnout.

He is also hoping to attract strong support from white voters without college degrees, who made up 36 per cent of the vote in 2016 and threw 57 per cent support to him.

Things may not be so easy, after Mr Biden surprised the nation with double digit wins among white women across the country. Should those results hold on Tuesday, it would likely bode very poorly for Mr Sanders, who has led in most polls this season but has seen some worrying 20-point deficits in two polls in the state after Super Tuesday.

Will coronavirus impact the race?

It just may. In Washington, the state with the second most delegates up for grabs, the virus has hit particularly hard in the Puget Sound area, where the state’s largest city Seattle is located.

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The Washington secretary of state has told voters to use water to seal mailed ballots, citing concern around the spread of the virus through the mail.

It’s really not clear what impact the virus will actually have, although a switch from precinct caucuses to a primary system over the past four years will make things a bit more competitive.

Washington is a mail in ballot state, so coronavirus may have relatively little impact, but the warnings from health officials aren’t the greatest sign. Mr Sanders won the state overwhelmingly in 2016, with 72 per cent of the vote.

How are the other states looking?

Missouri stands out as being one of the closest in 2016, and Mr Sanders lost by just about 1,500 votes. This year, Mr Biden has opened up a huge lead after things were relatively close just before Super Tuesday. The most recent poll shows him up by 30 per cent.

In Mississippi, Mr Biden is also expected to scoop up a good share of the state’s delegates, riding on his popularity among the state’s large number of African American voters — who make up around 71 per cent of the vote.

Idaho is meanwhile expected to break towards Mr Sanders, after he won the state with nearly 80 per cent of the vote in 2016.