Ahmed Moor, a Palestinian American, said he would run in a primary to be the Democratic nominee in 2028

John Fetterman, the maverick Democratic senator who has provoked widespread anger by increasingly siding with Republicans, is to be challenged for his Pennsylvania seat by a democratic socialist candidate who is originally from Gaza.

Ahmed Moor, a Palestinian American, said he would run in a primary to be the Democratic nominee in 2028, when Fetterman’s seat is up for re-election.

The move is the first sign of Fetterman’s weakened position in the party since the Democrats won back control of the Senate in last week’s US midterm elections, when the party won at least 54 of the upper chamber’s 100 seats.