Conservatives increasingly have to be all in, heaping praise on Mr. Trump's behavior or scolding those who criticize it. Defending protectionism, denouncing in toto the "witch hunt" and parroting Mr. Trump's ad hominem style is expected, and rewarded. For instance, the anti-tax group Club for Growth is trying to lure Rep. Mark Walker to challenge Sen. Thom Tillis in the North Carolina Republican primary. Why? Mr. Tillis has been insufficiently celebratory of Mr. Trump, demonstrated by the senator's brief opposition to an "emergency declaration" to fund a border wall (which Mr. Tillis ultimately voted for). Businessman Garland Tucker is already in the race charging Mr. Tillis of being insufficiently Trumpy. The Senate Leadership Fund, a super PAC, meantime, is defending Mr. Tillis by accusing Mr. Tucker of being an "anti-Trump activist."