In regards to the Democrats, they suffered a lethal blow to their party in 2016. Instead of trying to address the growing differences within their party, they masked it and tried to use Trump as a lightning rod to unite the entire party around. That seems to have worked to a lesser or greater extent, in combination with the lockdowns and the riots. The problem is that once Trump is out of the picture, the party will turn upon itself. Even while Trump was in office, you saw squabbles between voting blocs. That will get worse. We've already seen some of this over the summer.
As for the parties right now, there is a 4-way split in politics.
In regards to the Republicans, it's the Trump populists versus the neocons and the business community. Both of them are heavily invested in a globalist America that patrols the oceans and maintains its power across the world. These are in direct conflict with the Trump populists, who are protectionists (in that they want their businesses protected) and nationalists (who want the country's good to come before anyone else's). The problem for the old Republican politicians is that they cannot win an election WITHOUT those populists and said populists are very sensitive to those who don't put up. Talking the talk is nice, but unless you walk the walk, your ass is out next election.