Not saying Trump can't win again.
He enjoys campaigning and being a huge jerk and it is tricky for conventional pols to go against that and all the free media Trump gets.
But I think his chaotic presidency, violation of every norm, and all the scandals and impeachment will sandbag him. I think the GOP would be best served, certainly long-term, by having Trump removed and having a more regular GOPer such as Pence run.
Dems need to start working hard to win the Senate.
Get all the Dem candidates talking about the need to retake the Senate and get progressive policies enacted, and Obamacare saved. It should be something each candidate mentions during the next debate. Warren or somebody should should come out strongly on that, and get everyone else to agree and pledge what they'll do with a total Dem Congress.