Larry Sabato, a UVA political scientist, said the split between establishment and populist Republicans is an “extension of 2016” when the bulk of traditional party members supported someone else, but Trump won the nomination anyway. “The No. 1 reason Roy Moore lost is Roy Moore,” Sabato said. “I don’t know how much Bannon is to blame.” But to the extent that Bannon can fundraise and use his role as head of Breitbart News to promote anti-establishment candidates, Sabato said, “he is a problem for the Republicans.”