CLEVELAND — One of the last times you saw Ted Cruz, flames were shooting from his head and spittle was flying from his mouth — metaphorically, at least — as he branded Donald Trump “a pathological liar,” “a serial philanderer,” “utterly amoral” and a “narcissist” on a level this country had seldom seen. It was the day of Indiana’s Republican primary, Trump had just insinuated a connection between Cruz’s father and the assassination of John F. Kennedy, and Cruz announced that he must at long last tell the world “what I really think” of Trump.

But when you see the Texas senator on the convention stage here on Wednesday night, that contempt and candor will be absent. He may not exactly praise Trump, but he’ll almost certainly swallow whatever misgivings he still feels, and his presence alone will be taken by some viewers as a gesture of implicit, tentative support.

It will also be an example of what he always says he can’t stand about other politicians and what voters loathe as well: the elasticity of their convictions, the urgency of their self-interest and the alacrity with which they take an eraser to their past words.

There’s a lot of erasing going on these days, and Trump is a big reason. For many Republicans, rallying round him means conveniently forgetting how much they disagreed with or even detested him before, a breach much wider than the one that typically exists between opponents within a political party.