Paul Begala on CNN just made an interesting point about Biden "collapsing":

[Jarqui]

15. Hillary was in a much stronger position than Joe on Jan 2, 2008 +21.6

She had held a commanding lead over Obama and everyone else since the outset of the campaign - back to 2006.

Just 40 days later, on Feb 13, 2008, Obama gained 21.9 points and passed her for good.

A key was Obama winning Iowa. That got him more air time and national media notice, etc. The rest is history. Warren, Sanders & Buttigieg are all looking like they will beat Biden in Iowa. They seem better organized there.

I do not see an Obama in the field. Some might
https://www.huffpost.com/entry/pete-buttigieg-pitches-barack-obama-iowa-bus-tour-2020-democratic-presidential-primary_n_5dc44e2be4b0d8eb3c91c9f5
but relative to the leader, Warren is much better positioned at this juncture than Obama was

Biden is down to a 7.7 point lead more than two months sooner than Hillary - before the voting has even started. That's a lean - not likely or safe.

I think the world of Joe. But this primary is a long way from being over. He's far more vulnerable than Hillary was in 2008.