Trump’s Spring Revenge Tour Routed G.O.P. Foes. But Fall Headwinds Loom.

He has used his sway with his base to oust wayward Republicans more than he has made inroads with the independents his party needs to defeat Democrats in November.Representative Thomas Massie, center, after his concession speech on Tuesday in Hebron, Ky. Mr. Massie, one of President Trump’s most outspoken critics in Congress, was ousted by a primary challenger.