This is it. I’ve got to believe he’s not running. He wouldn’t use the White House as a campaign prop, right?

Stand by for updates.

BREAKING: Vice President to make statement at White House at 12:10p ET

— CNBC Now (@CNBCnow) October 21, 2015

Update: Obama will be there too, apparently, which means Biden’s definitely not running. No way would O symbolically endorse him that way.

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12:10PM THE VICE PRESIDENT delivers a statement; THE PRESIDENT will also attend

— Rebecca Buck (@RebeccaBuck) October 21, 2015

Update: And there you go.

BREAKING: Sources close to @VP @JoeBiden tell @CBSNews he will not launch a presidential bid.

— David Goodman (@davidgoodmanTV) October 21, 2015

That sure is a sudden turnaround in the span of a week. Every report I’ve seen in the last few days, most notably this one from Fox News claiming that he was about to jump in, said he was a go. Maybe he changed his mind at the last second? But why?

Update: Biden announces he’s not running. With him goes any mystery about who the Democratic nominee will be.

Update: He says the window has closed on running a winning campaign, which you can interpret as either (a) an acknowledgment that Hillary did well enough at the debate last week to make a Biden candidacy superfluous to centrist Dems or (b) an admission that he simply dragged his feet too long in deciding whether to get in. Hard to believe an old pro like Biden with plenty of aides might have been at risk of missing any key deadlines, but there were a lot of them — and coming to grips with the sheer logistical challenge of running this light might explain Biden’s apparent last-minute decision not to run. Maybe he was inclined to jump in and then sobered up once he realized how much work was still left to do just to qualify for the ballot. Hard to believe, but I don’t know why the rumors of a candidacy would be so wrong otherwise.

Update: For an “I’m not running” speech, he sure did go on and on at the podium — and sounded a lot like a candidate in doing so. I think this is more of an “I’m not running, unless” speech, actually: Just in case the DOJ shocks the world by indicting Hillary or another scandal blows up in her face, Biden’s letting Democrats know that he’s a solid Plan B. In case of emergency, break glass and vote Joe.

Update: Pretty much.

What you're hearing is a guy who thinks that of the pack he'd be the best president but knows he has no path to it

— Jake Tapper (@jaketapper) October 21, 2015