WASHINGTON—President Donald Trump has weighed in on the race to replace the late Lindsey Graham in the Senate, calling on his sister, Sen. Darline Graham Nordone (R-S.C.), to run for his seat. “Darline, who comes from an absolutely incredible family, has been a winner all of her life and, should she accept, has my complete and total endorsement in the special election for U.S. Senate in South Carolina,” Trump wrote on Truth Social on July 17. Graham, who had served in the Senate since 2003, passed away on July 11 after a cardiac episode following a trip to Ukraine. He won the Republican primary for his seat in June....