Why tonight’s debate matters so much to Joe Biden

Former Vice President Joe Biden has benefited, to borrow a phrase from a man who once held the office he is seeking, the “soft bigotry of low expectations” so far in the 2020 presidential debates.

Biden entered the race in the spring as the clear front-runner in the Democratic field. Since that time he has appeared in three debates with a varying cast of Democratic characters. His performances in those debates have ranged from “not bad” to “oh man.” Biden’s best debate was the last one in Houston, in which he started quite strong and authoritative but faded badly as the debate wore on —  culminating with an answer on reparations for slavery that was cringingly bad.

Despite mediocre-ish performances, Biden has, generally speaking, not suffered greatly in the media after-action reports. (I, myself, named Biden a “winner” in the last debate, noting that he did just enough to keep the wolves from his door and benefited greatly from the widely panned attack on his age/competence from Julián Castro.)

But even between the last debate and the one tonight — 8 p.m. on CNN! — things have changed for Biden — and make a so-so debate performance harder to write off.

First, this is the FOURTH Democratic debate. If the first one or two were Biden getting his sea legs after years of not being a candidate for national office, then he has to have moved beyond that feeling-out period by now. If he hasn’t, it’s evidence that something bigger is wrong.

Second, Biden is no longer the clear front-runner. You can argue whether he or Massachusetts Sen. Elizabeth Warren is more likely to get the nomination at this point, but it’s definitely an argument. What’s beyond argument is that Biden has lost any sort of wiggle room in the race. He can’t just give away a few points after a weak debate performance now, because if he did, he’d be clearly behind Warren.

Biden then can’t just be “good for Biden” tonight. He has to be good. Period.