Joe Biden, Donald Trump win Michigan primaries

US President Joe Biden and former president Donald Trump have won the presidential primaries in Michigan, further solidifying the all-but-certain rematch between the two men.

Biden easily won the Democratic presidential primary, Edison Research projected, but a protest vote by Democrats angry over his support for Israel’s war against Hamas in Gaza was showing signs of strength as returns were counted.

Trump won the Republican presidential primary in the US state by a large margin, Edison projected, further strengthening his grip on the party’s White House nomination as Nikki Haley, his last remaining rival, came in a distant second.

Although Biden and Trump had been expected to easily win their separate party primaries, Tuesday’s vote (Wednesday AEDT) count for both was being closely watched for signs of wavering support.

In Michigan, home to a large Arab American constituency, Democratic voters had been urged to mark their primary ballots as “uncommitted” in protest at Biden’s Gaza policy.

Early returns showed Biden and Trump with solid overall leads. With 10 per cent of the estimated Democratic vote counted, Biden had 80 per cent support, with “uncommitted” getting 15 per cent, and with 17 per cent of the estimated Republican vote counted, Trump had 66 per cent support to Haley’s 29 per cent, according to Edison.

Michigan routinely offers an “uncommitted” option as a way of questioning whether a named candidate has the support of the party’s base. It could not be determined how many of those votes were protesting Biden’s Gaza policy.

Michigan is expected to play a decisive role in the head-to-head November 5 US presidential election, a likely rematch between Biden and Trump.

It is a battleground state that could swing toward either party. Biden beat Trump in Michigan by just 2.8 percentage points in the 2020 election.

Michigan turnout for former UN Ambassador Haley, who won nearly 40 per cent of Republican votes in her home state of South Carolina on Saturday, was also being scrutinised for signs of vulnerability for Trump among moderates, whose support he would need in a general election.

Despite having lost to Trump in every primary race, Haley has performed well with moderate voters and has vowed to carry on despite having no clear path to the nomination.

On Tuesday, shortly before Trump was projected the winner in Michigan, Haley vowed to carry on.

“We’ve only seen a handful of states vote,” Haley told CNN. “We’re taking this one state one day at a time.”

Many in Michigan’s Arab American community who backed Biden in 2020 are now outraged, along with some progressive Democrats, over Biden’s support for Israel’s offensive in Hamas-ruled Gaza where tens of thousands of Palestinians have been killed.

Agencies