If the Democrats screw this up, which unfortunately is something they're good at, there's going to be a lot of reasons why, but I suspect that a major reason is this: everyone kinda knows there's a bunch of senile old farts in politics, quietly being shepherded around by staff and still able to go through routine political motions, and nobody wants to talk about it openly.
Except, of course, for the GOP.
The Democrats have never learned that they can't get away with sharing mutual vices with Republicans. I've talked sarcastically about the purported affability of President Ronald Reagan (R) with Speaker of the House Tip O'Neill (D) and the bipartisan camaraderie that's supposed to have flourished on Capitol Hill in the 1980s. It's mostly bullshit, of course, but there's a discreditable underlying truth: the Reaganite Republicans were spectacularly corrupt, but O'Neill and other prominent Democrats were also corrupt, and the Democrats had a lot of skeletons they were trying to keep out of sight. (See also Robert Byrd!) Yes, there was some sort of equilibrium, but it was the uneasy social relationship of a blackmailer with their victims. The Democrats were dirty, and thus vulnerable. What did they do about that? Why, they got even dirtier of course.
Basically I suspect that some sort of under-the-table "gentleman's agreement" had once existed between the Republican and Democratic congressional factions to keep the senility of their people secret. Surely both were guilty of hiding it. If this in fact happened, it was a mistake for the Democrats to trust the GOP to uphold a devil's bargain like that, because they get so much mileage out of backstabbing the Democrats with such things. The Democrats are always taken by surprise. I surmise that the Republicans are threatening to out a whole bunch of Democratic politicians at once, and that might be what's driving the "Dump Biden" bandwagon among the Democrats.
Once again, they've fucked themselves. It was always grotesquely irresponsible for politicians like Speaker Pelosi and Senator Feinstein to cling to office term after term simply because they could, because they'd sewn up their districts and wouldn't ever really have to face a challenge ever again. The Democrats seemed to be taking a perverse pride in racking up years of loyal public service, like "The Simpsons" refusing to die merely because they've got records left to break. And I think the GOP knew exactly where to land their blows on all fronts.
(growls) Once again I must ask, why do the Democrats have to make this so difficult??
~Chara of Pnictogen