Just one day out from the crucial Michigan primary, a new poll shows Joe Biden leading Bernie Sanders by 24 per cent among Democratic voters in that state.

The results illustrate the incredible degree to which moderate Democrats have managed to coalesce and put their might behind Mr Biden, after other candidates who were hoping to occupy the centrist lane dropped out and announced their endorsement of the former vice president.

And, should those results pan out on Tuesday when voters in the state head to the polls, the impact could be to blunt the once seemingly unstoppable momentum of Mr Sanders, who stunned the nation four years ago by beating Hillary Clinton there and dragging down her eventual march to the nomination.

“Every state is terribly important, and I think coming Tuesday, maybe Michigan is the most important state,” Mr Sanders told reporters on Friday while campaigning in Detroit.

The new poll, conducted by pollster EPIC-MRA for the Detroit Free Press and released on Monday, gives Mr Biden a 51 per cent to 27 per cent lead in the battleground state, which helped to deliver Donald Trump his own surprising victory over Ms Clinton in 2016.

“Something happened on Super Tuesday with (other) candidates getting out and people are all of a sudden questioning Bernie’s positions on issues,” said Bernie Porn, a pollster with the company, told the newspaper.

Another new poll, conducted by Mitchell Research & Communications and released on Sunday, gave Mr Biden 54 per cent support in the state, followed by Mr Sanders with 33 per cent. Voters were asked about several other candidates as well, but virtually every other competitive candidate has dropped out of the race.

And that includes voters who have already cast their ballot in early voting — 69 per cent said they supported Mr Biden, and 18 per cent said they cast their ballot in favour of Mr Sanders — as well as those who still need to vote — Mr Biden attracted 49 per cent among that group, while Mr Sanders got 39 per cent.

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There is some reason for caution when reading those numbers, however.

The Mitchell Research poll is generally viewed as somewhat unreliable by the analysts at FiveThirtyEight, and the 2016 election brought some surprises that deviated widely from what the Free Press and EPIC-MRA poll showed at a similar stage in the race.

That poll showed Ms Clinton with a 25 point lead over Mr Sanders, and the Vermont senator ultimately went on to win the state with a narrow 1.4 per cent margin.