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.

© Eric Lee/The New York Times; Joel Angel Juarez/Reuters

The Trump administration’s policies could cost Republicans in a state that is being hit hard by expensive diesel prices and uncertainty over trade.

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.

© Kenny Holston/The New York Times