No. of Recommendations: 3
I think it's more of a divot, than a hole
It's not a divot, and probably not even a hole - it's a chams.
This wasn't just one bad night, because campaigns don't "restart" like baseball games after the 9 innings are over. The first fifteen minutes of the debate (and his closing statement, perhaps) will be on continuous playback for the rest of the campaign. The next four months will be filled with Trump PAC campaign ads showing Biden's all-but-incapacitated responses, a never-ceasing loop of "We beat Medicare." This was not a one-time thing that "only" 50 million people watched - this is a debacle that will affect the rest of the campaign.
There are numerous terrible consequences for Biden's chances. The first, most obvious, is that some persuadable voters will no longer vote for Biden. They'll conclude he's simply too mentally impaired to be President. And some will vote for Trump, which doubles the negative impact.
The second is that this creates a permission structure for Republicans and GOP-leaners who are worried about Trump's many flaws, and who might have voted for Biden, to go ahead and vote for him anyway. It's hard to vote for a convicted felon....but if the alternative is actually mentally unfit to some extent, it's much easier to get past that cognitive dissonance.
The third is that this issue will dominate the campaign until at least the next debate, eating up valuable time where Biden will have to play defense ("It's a referendum on Biden") rather than offense ("It's a choice between Trump and Biden."). And it's a bad issue for them, especially since the Biden campaign has been so dismissive of concerns about his age, which is going to pose a lot of credibility problems for his surrogates.
* * * *
There are no good options for Democrats. They are now very likely to lose the Presidency, and there may not be anything they can do about it. If Biden were to step aside, that doesn't mean they're going to win - and it may be that they can't win even if he did step aside. Harris isn't especially popular, has her own faults as a campaigner, would still have to run on the Biden/Harris record, and would have to answer some pretty tough questions about how she didn't see that Biden was so incapacitated that he couldn't be the nominee (or why she didn't do anything about it). If it's someone other than Harris, the process of getting to them could end up splitting the party - and even then, no guarantees they fare any better on the national stage (with the handicap of going from zero to Presidential nominee with only three months to the election).
And again, it's still very unlikely Biden will step aside. He knows all of the above. He knows that regardless of whether a different nominee could have crushed Trump had Biden chosen not to run last summer, now any new nominee is very unlikely to win. He's not going to step aside even if he has an epiphany that he's not a great candidate (regardless of whether he's been a good President) unless he's also convinced that the party would likely land on a better candidate in a way that helped them win. It's hard to see him getting there.
Their best option might be to simply take the "L" at the top of the ticket and do what they can to save Brown and Tester and other down-ballot candidates.
