The most powerful Democrat alive, arguably the most popular politician in a generation, decided to wait to endorse the standard-bearer of his legacy until after it actually mattered.

A full day after Bernie Sanders backed Joe Biden, Barack Obama has finally buckled and endorsed his former vice president. The show of unity is no doubt a light at the end of this quarantine tunnel for millions of Democrats. But it also raises a crucial question: Why now?

Unlike Hillary Clinton in 2016, Biden was never headed to a coronation. The establishment held out at first for a younger and more, as they say, "intersectional" candidate. Alas, Biden became Democrats' last resort when it came down to him and a curmudgeonly communist who's never met a dictator he doesn't love. Only then did the sane candidates of the field bow out and fall in line.

Biden underwent a full year of naysaying, tsk-tsking, and completely fabricated news cycles from the media. Not one person with an iota of power in the party came to his defense, and at a couple of different moments, his bid appeared to be doomed. Obama pointedly refused to get behind his former vice president. Then he turned it all around in the span of 100 hours. Biden blew out the competition in South Carolina, then earned the endorsements of half the presidential field. On Super Tuesday, he ended Sanders's dreams of a socialist presidency.

Biden did all this without Obama's help. And now, with the country corona'd-out, and even poor old Joe stuck livestreaming from his basement like a teenager grounded for skipping curfew, Obama has finally condescended to endorse Biden via video.

Obama's backing is not a magic bullet, as the monumental losses by Hillary Clinton, Stacey Abrams, Andrew Gillum, and Bill Nelson all proved. But his belated contribution of a homemade video tells us all we need to know about how thrilled Obama must be to have a borderline-senile white guy responsible for carrying on his legacy.