The 3 questions implied here are:

1. Why is this so fucking hard?

2. Who is actually in charge at the DNC (hint: it has to do with money and buried histories/influence)?

3. Who else does the DNC actually have that's ready to step into the "viable candidate" job?

Bonus question: What, actually, IS the job that needs doing?

#1 is easy to answer because the answer to the rest is always, "Huh?"

Trump isn't going to get elected for being shot at; he's probably going to get elected because there is no coherent competitor. The DNC proved it in 2016, and nothing has changed in their minds. They still blame "deplorables" instead of themselves: the educated who failed to educate those deplorables(TIAA/CREF is not an education system, even if their lawyers bludgeoned small school boards into believing it is).

Biden's na narcissism is apparently a plague of scholarly Ivy League blindness. Half of the country votes democrat because they still believe in wise leadership, science, cooperation, education and decency. Too bad the DNC doesn't know what those things are. They get guidance from rich donors who cynically say "It's the Economy, Stupid!" and make decisions based on winning contests of competitive moral turpitude. Is it any wonder people are starting to hope for SkyNet?