A victory for Biden in Arizona would give the Democrat 11 electoral votes, a major boost in his bid to win the White House, while severely narrowing Trump's path to re-election, in a state the Republican won in 2016.
MI has been on edge for months over fears of political violence.
Several large pro-Trump protests converged at election counting locations in MI and Arizona on Wednesday, one day after Tuesday's yet-to-be-called presidential election.
A similar scene played out on Wednesday afternoon in downtown Detroit, where city election officials blocked about 30 people, mostly Republicans, from entering a vote-counting hall amid unfounded claims that the vote count was fraudulent. "Stop the steal!" they said in Phoenix. "An accurate vote takes time".
The AP's projection comes hours after the Trump campaign filed a suit to halt counting of ballots in MI after they argued the campaign hadn't been given "meaningful access" to observe the opening of ballots and the counting process.
Trump campaign announces lawsuit being filed in Nevada to stop ballot counting
That's nearly exactly what happened early Wednesday morning - altered slightly by a speedier timeline than what Sanders predicted. Even some conservative news pundits have cautioned Trump supporters to not believe everything that they hear from the campaign.
The anti-Trump site The Recount put together a split-screen video contrasting the protests - and the conflicting messages - in the two locations.
Republicans are hoping to challenge the vote and claimed they were unfairly being kept outside where the absentee ballots are being counted.
On Election Night, scattered protests broke after voting ended, stretching from Washington, DC, to Seattle, but there was no widespread unrest or significant violence.
Richard March came to an anti-Trump demonstration in Portland despite a heart condition that makes him vulnerable to COVID-19.
The prolonged task of counting this year's deluge of mail-in votes raised fears that the lack of clarity in the presidential race could spark conflict.