Again, Democratic party isn't a single party. The First Past The Post is mathematically leading to two dominant parties. That's why we currently have Republicans vs everyone else. If Republicans pay would get dissolved Democrats could easily split into conservatives and progressives.

If we want to have more parties the only way is either to change to proportional representation (the number of seats is determined by the percentage of views won) kind of difficult to change in US.

Or replace FPTP with RCV.

This is why MAGA didn't start as a separate party and instead hijacked Republicans. Progressives need to do the same with the Democratic party.