Retiring Sen. Jeff Flake (R-Ariz.) recently said that someone should challenge Trump in the 2020 primaries “to remind Republicans what it means to be conservative, what being a conservative really means and what it means to be decent” — even as he has voted with Trump more than 80 percent of the time.

If nominated, such a candidate could in theory win back the suburban voters who just reduced Republicans to a minority in the House for the first time in a decade. There’s just one problem: A candidate who ran on anti-Trump finger-wagging has no chance of winning the nomination for the foreseeable future. Much of the GOP base likes Trump’s rudeness and pugilism. It’s a feature, not a bug.

Flake himself is a case in point. He did not run for re-election in large part because he did not think he could win a Republican primary criticizing, though only occasionally voting against, Trump. If he somehow pulled off a rapprochement with Trump in time for the late primary, he would not have been able to adjust for the general election in time.