Voters in Michigan headed to the polls Tuesday for a US presidential primary expected to be another ticker-tape parade for Republican Donald Trump -- but could deliver Democratic leader Joe Biden a bloody nose over the war in Gaza.
Biden, 81, faces no serious opposition to being nominated as the party's nominee.
But as the civilian death toll mounts in the conflict between Israel and Hamas, he has seen support erode among Muslims and Arab Americans, a bloc crucial to his narrow 2020 victory in Michigan over Trump.
The midwestern state has the largest proportion of residents who identify as being of Middle Eastern or North African descent in the country, with most of the population concentrated around Detroit.
Activists in the key battleground state -- where Biden's winning margin four years ago was a mere 150,000 votes -- want Democrats to vote "uncommitted" to pressure the president to back off from his Israel support and call for an immediate ceasefire.
"I was proud today to walk in and pull a Democratic ballot and vote 'uncommitted,'" said Representative Rashida Tlaib, the only Palestinian American in Congress.
"Seventy-four percent of Democrats in Michigan support a ceasefire yet President Biden is not hearing us, this is the way we can use our democracy to say 'listen to Michigan,'" she said in a video on social media.
The protest movement, Listen to Michigan, hopes to amass 10,000 uncommitted voters.
That won't stop Biden's easy march to the nomination, as his main would-be rival, Minnesota congressman Dean Phillips, polls in single digits.
But a significant number of protest votes could set off alarm bells ahead of the November general election, when Biden cannot afford to lose even a fraction of his coalition in the swing state.
The war started when Hamas attacked Israel on October 7, resulting in the deaths of about 1,160 people in Israel, mostly civilians, according to an AFP tally of official Israeli figures.
But concern has mounted amid the high civilian death toll in Israel's retaliatory campaign, now at almost 30,000, according to the health ministry in Hamas-run Gaza.
A similar write-in campaign calling for a ceasefire during the New Hampshire primary went nowhere, but Michigan has a significantly larger Muslim and Arab population.
Abdullah Hammoud, the mayor of Dearborn, a heavily Arab American suburb of Detroit, said that Tuesday's vote was about "holding President Biden accountable."
And Fatima Elzaghir, a 27-year-old nurse told AFP that she wanted her "uncommitted vote" to force Biden to change.
"I think it's evident that appealing to human empathy does not sway most politicians so maybe wanting to win Michigan will pressure him to ceasefire," she said.
On the Republican side, Trump has swept the early voting states and Michigan is not expected to interrupt his march to the nomination.
His sole remaining challenger, former UN ambassador Nikki Haley, lost her home state of South Carolina to Trump at the weekend but has refused to quit, saying she doesn't believe Trump can defeat Biden.
"We are in a ship with a hole in it. You can either ignore the hole and go down with the ship, or you can acknowledge that we've got to look for a life raft," she told CNN Tuesday morning.
Haley suffered another blow Sunday when the wealthy Koch family network said it was halting its donations to her campaign.
Both parties hold votes on Tuesday, although Republicans have adopted a complex hybrid system that wraps up the contest four days later via caucus-style gatherings in each of the state's 13 congressional districts.
More than two-thirds of Michigan's Republican delegates -- the individuals appointed to back candidates at the party's summer nominating convention -- will be awarded on March 2.
