Donald Trump must have neglected to watch the video of Ronald Reagan in his 1980 debate with President Carter. Had he copied the restrained and imperturbable approach of Reagan—or at least tried to—Trump could have benefitted enormously from last night’s debate with Hillary Clinton. But he didn’t. And that was his biggest mistake.

Instead, he resurrected the rowdy Trump of the Republican primary debates. He talked too long, interrupted Clinton, touted himself, and took her bait time after time to respond to her charges. It was the wrong approach at the wrong time at the wrong debate.