Biden, a Democrat, and Republican former President Donald Trump will both want strong showings in their separate nominating contests. Michigan is a battleground state expected to play a decisive role in the head-to-head Nov. 5 election.

Many in the large Arab American community are outraged, along with some progressive Democrats, over what they assert is Biden's unwavering support for Israel's Gaza offensive in which tens of thousands of Palestinians have been killed.

Late on Monday, Biden said Israel had agreed to halt military activities in Gaza for the Muslim holy month of Ramadan expected to begin on the evening of March 10, as Hamas studied a draft for a truce that includes a prisoner-hostage exchange.

The effect on the vote in Michigan remained to be seen.

In the run-up to the primary vote, Rashida Tlaib, a Michigan Democratic congresswoman and Palestinian American, had urged Democratic primary voters to not vote for Biden on Tuesday and to instead mark "uncommitted" on their ballots.

The uncommitted campaign, backed by Arab American leaders, won support, including in Dearborn, a city where nearly 55% of its 110,000 residents are of Middle Eastern or North African ancestry, most of them Arab, says the U.S. Census Bureau.

On Sunday, Michigan Governor Gretchen Whitmer, a Democrat, pushed back against the uncommitted campaign. She warned that if Democrats failed to support Biden, it could hand the swing state and the country to Trump in November.

"It's important not to lose sight of the fact that any vote that's not cast for Joe Biden supports a second Trump term," Whitmer told CNN's "State of the Union."

She reminded people of Trump's travel ban on people from Muslim countries when he was president. "A second Trump term would be devastating," Whitmer said.

Waleed Shahid, a senior Democratic strategist and adviser to the Listen to Michigan group behind the uncommitted vote, said: "When voters choose uncommitted over President Biden in this primary, what they're saying is we are uncommitted to President Biden's reelection until he stops funding Israel's war in Gaza."

A senior Biden campaign official said: "We're taking this seriously. The president himself has said repeatedly that he hears these demonstrators and that he thinks that their cause is important."

The official added: "This is not a cause for panic. Michigan is big and has many different constituencies and overall, we have a good story to tell there."

On Feb. 1, Biden won a strong pledge of support from union autoworkers, a Michigan voting bloc no less crucial to his reelection bid. The state is home to nearly 20% of all U.S. auto production, more than any state in the country.

"We are going to keep highlighting the contrast between Biden and Trump and once that becomes clear, we fully expect these voters, who have walked away from Biden, to come back," said LaShawn English, UAW Director Region 1, which represents eight counties in Michigan.

MICHIGAN A BATTLEGROUND FOR SUPPORT

Biden beat Trump in Michigan by 2.8 percentage points in the 2020 election. Trump beat Democrat Hillary Clinton there by less than one percentage point when he won the presidency in 2016. Those results explain why both candidates want to shore up support now.

"Those who are pushing for the uncommitted vote for Tuesday should be careful what they wish for because Biden is trailing Trump in our statewide polls in Michigan. Biden is underperforming right now, and this uncommitted movement could hurt him in November," said Bernie Porn, president of Michigan-based research firm EPIC-MRA.

Hamas fighters infiltrated Israel on Oct. 7, killing about 1,200 people on the deadliest day for Israel in its 75-year-old history and taking some 240 hostages back to Hamas-ruled Gaza, according to Israeli tallies.

In the four months since, Palestinian authorities say Israel has killed nearly 30,000 people in Gaza and displaced most of its 2.3 million people. Israeli leaders say they remain committed to wiping out Hamas.

Biden has been supportive of Israel while pushing for more humanitarian aid to Gaza and has faced criticism from some Democrats for not backing a ceasefire in the Palestinian territory,

On the Republican side, Michigan this year will allocate its delegates to July's party convention based on both Tuesday's primary, open to all voters, and a March 2 caucus in which active party members choose the nominee.

Beset by chaos among warring factions, the Michigan Republican Party will hold competing caucus meetings on March 2. Nonetheless, Trump is expected to easily win the Tuesday primary and the March 2 caucuses. Opinion polls show him holding an average statewide lead of nearly 57 percentage points over rival Nikki Haley, says the poll tracking website FiveThirtyEight.

The results in Michigan will be watched to see how much Trump struggles to attract large numbers of moderates and traditional Republicans, voters he will likely need to win back the White House in November.

Trump has soundly defeated Haley in all the nominating contests so far, but Haley has performed well with moderate voters, exposing a potential vulnerability for Trump in the general election.

After losing to Trump in Saturday's primary in South Carolina, her home state, Haley vowed to carry on despite having no clear path to the nomination. She campaigned in Michigan on Monday and will visit many of the 15 states that vote on March 5, known as "Super Tuesday."

(Reporting by Nandita Bose in Detroit and Tim Reid in Washington; Editing by Howard Goller)

By Nandita Bose and Tim Reid