As voters head to the polls in five states across the country for "Big Tuesday", the latest predictions show Joe Biden sweeping each state in what would be a devastating blow to Bernie Sanders and what appears to be his increasingly long odds of becoming the Democratic nominee.

While close, the primaries across the country could serve as a clarifying moment in the campaign, especially if Mr Biden pulls off decisive wins that cement his status as frontrunner.

The projected wins, as compiled by the website FiveThirtyEight, would include states that Mr Sanders won just four years ago against Hillary Clinton, who eventually became the nominee after a long nominating season that saw both candidates slogging it out until the end.

But Mr Biden may open up a wider lead on Tuesday, when Michigan, Washington, Missouri, Mississippi, Idaho and North Dakota head to the polls.

In Michigan, which has been seen as a crucial state for Mr Sanders after he won there in 2016 with 29.8 per cent of the vote, Mr Biden has pulled ahead over the past week or so, and is being given 99 per cent chance of winning the most votes in the state.

In Washington, which Mr Sanders won in 2016 with 72 per cent of the vote, Mr Biden has also pulled ahead in recent polls. The former vice president has been given a 60 per cent chance of winning the most votes there.

Missouri appears to be another strong state for Mr Biden, after sweeping through the South on Super Tuesday, relying on strong support from African American voters there. He has been given a 99 per cent chance of winning that contest. Mr Sanders lost in 2016 to Ms Clinton, who got 49.6 per cent support compared to Mr Sanders’ 49.4 per cent.

Mississippi, meanwhile, is another projected blowout for Mr Biden, with a projected 99 per cent chance of him winning the most votes there. Ms Clinton received 82.6 per cent of the state’s vote in 2016, compared to Mr Sanders’ 16.5 per cent.

Idaho so far appears to have a closer race for Mr Biden, though he still has an 81 per cent chance of winning, compared to Mr Sanders’ 19 per cent chance. Mr Sanders received 78 per cent of the vote in 2016, compared to Ms Clinton’s 21.2 per cent.

North Dakota is also projected heavily in Mr Biden’s favour, with him having a 93 per cent chance of winning there. Mr Sanders won the state with 64.2 per cent of the vote, compared to Ms Clinton’s 25.6 per cent.

One final election result can be expected on Tuesday night from Democrats abroad, who have been voting in recent days. Mr Biden has been given a 65 per cent chance of winning the most votes among those Democrats.

Beyond those projections, Mr Sanders and political observers will be watching to see how much of a margin Mr Biden might run up.

Since the states are not winner-take-all, Mr Sanders could still amass a notable number of delegates on Tuesday, and potentially stay competitive in the days head.