So one would think that if a Congressman or Senator actively supported Trump and his evil and unpopular actions, that they would be in jeopardy. Unfortunately, that might not be the case at least in part, IMNVHO, that Trump is so extreme that Republicans are willing to consider him an aberration and think that even if they don't like him, their own slobbering right-wing extremist, who now looks almost "normal" compared to Trump's bunch, would be just fine after Trump's gone. So a lot of them are going to keep voting against their own interests and try to keep the enablers and accomplices in office.
But really, Dems don't need any of the slobbering hard-core Trumpsters to turn in order to win elections. They do, however, need all the Dems and most of the nominal "independents" to actually show up to vote. And they need to put new faces on the party. They've let the Republicans define the party by demonizing P-Lo, by painting Dems as the party of illegal immigrants, atheists, welfare queens and WallStreet - not that their bullshit has to be logical or consistent to be harmful.

We need somebody who can draw and invigorate a crowd - in person and online - and that carries a message wide enough for lots of people to get behind. Just "I'm not Trump" isn't good enough. Nor is too much emphasis on polarizing issues. A position on abortion should be as simple as, "I support the rights defined and in effect for over 40 years, and will oppose any law changing or reducing those rights. And that's all I have to say about that. Next question." Steal Trump's infrastructure bit - that's popular with everybody, and he's certainly not going to use it. Steal the "America First" jingoism by defining a "great America" as one who leads, and one that is admired by citizens and other countries, not one that is a bully and aggressor. Create a wide-base platform, and conduct the best campaigns designed by people who know what they're doing. Run candidates that (in addition to basic qualifications) speak well, are scandal-free, look good on TV, are likeable, and follow basic rules of etiquette and common decency.
Otherwise, we'll be stuck with President* Trump and may even have to remove the asterisk in 2021.