The president contended that Dr. Abdul El-Sayed, a Muslim, would “invite hordes of jihadis to our shores” as he sought to bolster the G.O.P. candidate in a tight Senate race.
President Trump’s comments, coming in a key midterm battleground nine days before the elections, underscored the dark themes and personal vilification he and his allies have embraced as part of their closing pitch.
On the trail, James Talarico, the Democratic Senate nominee, has increasingly gone after Mr. Musk, a critic of his who has given big to a group aligned with the Republican candidate, Ken Paxton.
The vice president backed an advertisement featuring Democrat Amy Acton’s mother, who has been estranged from Dr. Acton since her stepfather was charged with child rape.