Sister of late Lindsey Graham, who has been backed by Trump, overcomes concern about lack of experience to win place on November ballot

• South Carolina chooses Darline Graham as Republican nominee for US Senate

Republican senator Dan S Sullivan will be joined on the November ballot in Alaska by a challenger with a nearly identical name from the same party, election officials confirmed on Tuesday, adding a twist to what is expected to be one of the most hotly contested races of the midterms.

The Republican senator is running for a third term against Democrat Mary Peltola, a former US House representative whom polls show is neck-and-neck with him in a state that hasn’t sent a Democrat to the Senate since 2008.