My Theory:
Biden's tied in with the Chinese. Probably owes 'em due to dealings with his son. Chinese have Biden over a barrel.
Any trade deal with US won't fly because China can't handle anything other than what they gave now. China gets Biden in a full Nelson and tells him to run because the only chance is to unseat Trump. China gives money and electronic 'help',
Rudy goes to Ukraine 'sniffing around' to let China know Biden ain't gonna make it. Takes that negotiation angle off the table. Warren's bitching because she's in on the deal. All house bullshit with the fat bastard, etc., too.
tl;dr China's only negotiation hope is to unseat Trump and go back to business as usual. Good guys will take out China's bought stooges as necessary to keep negotiation pressure on.