Serious question: are enough voters going to care what Trump has to say about his opponent for it to even make a difference in 2020 anyway? No, seriously. No one takes him seriously beyond the roughly 40% floor he has in the country. Everyone has learned to either tune the nonsense out or is immersed in the rage (and if you haven't, I'm so, so sorry. I have had to watch Fox News all day in the background at my parents' house, and it's literally something that would blow away even Goebbels at this point).
Bottom line here, Democrats going to need to nominate a decent strong candidate with a cleaner record.