Ameen Almudhari was one of thousands of people in the majority-Arab community of Dearborn, Mich., who helped Joe Biden win the city and defeat Donald Trump in the 2020 presidential election.

Four years later, Mr. Almudhari had had enough.

This week, he joined thousands of other Dearborn residents in voting for Mr. Trump, helping him score a stunning win in a place that seemed an unlikely source of support in the former president’s bid to return to the White House.

Standing next to his 10-year-old son outside an elementary school on the north side of Dearborn on Tuesday evening, Mr. Almudhari, 33, explained his change of heart, part of a remarkable turnabout in Dearborn, which is just outside Detroit.

He was, he said, fed up with Mr. Biden’s support of Israel and Ukraine and said the death and destruction being underwritten by the United States drove his decision to back Mr. Trump.

“The first time we vote for Joe Biden, but what we see right now, he didn’t stop the genocide in Gaza,” said Mr. Almudhari, a Yemeni American, who faulted the president for spending American money to support the wars in Gaza and Ukraine.

His son, Khaled, interrupted him with a smiling comment: “Trump will end the war!”

Indeed, Mr. Trump has said as much, and the promise was among a host of reasons cited by voters in Dearborn for the wave of support from Arab and Muslim Americans for Mr. Trump.