It’s plausible that Trump has placed his chips on knocking Biden out, not realizing that Biden was never the major challenge he appeared. Now that Biden is fading—for reasons that have little to do with Trump—what if the president embarked on a quixotic quest and ended up with nothing to show for it but the stain of impeachment?

Trump’s fear of Biden may have helped him seem like a stronger contender than he really was. Many head-to-head polls show Biden performing better against Trump than his Democratic rivals, but such polls are unreliable this far out. Besides, none of that matters if you can’t win the primary, and Biden’s weaknesses there were apparent long ago. Veterans of the Obama administration warned him off running four years ago—when he was four years younger and the Obama legacy was fresher. Pundits pointed out that his past bids for president had been shaky and come up well short. When the predicted collapse didn’t come early on, that conventional wisdom dissolved—but perhaps it was right, only premature.