Donald Trump singled out four of his challengers for ridicule on Tuesday, mocking Joe Biden, Pete Buttigieg, Beto O’Rourke and Bernie Sanders and predicting one of them will win the 2020 Democratic nomination. ‘Boy, you got some beauties there!’ he said during a speech in Louisiana about energy infrastructure. ‘Three hundred and fifty million people and that’s the best we can do?’ ‘It’s going to be one of these people,’ he said. So far 23 different Democratic White House hopefuls have declared their candidacies. He poked fun at O’Rourke for quickly losing what a month ago looked like juggernaut momentum....