PARIS — French nationalist Marine Le Pen has executed one of the most extraordinary political rebrandings in the Western world. She has transformed the fringe neofascist party founded by her father into a mainstream political force with a shot at winning a majority and naming the next prime minister.

       But as she and her deputy, Jordan Bardella, stand on the brink of what could be their greatest electoral triumph, innuendo, conspiracies and vitriol from National Rally candidates and supporters are amplifying doubts about how much a movement originally rooted in antisemitism and racism has truly evolved.