Republican presidential nominee Donald Trump escalated his war with his own party’s leadership Tuesday by refusing to endorse House Speaker Paul D. Ryan or Sen. John McCain, two of the GOP’s highest-ranking elected officials, in their primary campaigns. Trump said he was not backing Ryan in his primary election next Tuesday in Wisconsin, or McCain in his Arizona primary later this month. Both have endorsed Trump but have criticized some of his policies and statements, most recently his belittling of the parents of dead U.S. Army Capt. Humayun Khan. Trump’s statements about Ryan are the latest hiccup in what has been a fraught relationship for the two party leaders. Ryan endorsed Trump this spring and spoke on his behalf at the convention, but only after a period of public soul-searching.