The Democratic Party does have a progressive wing, but you still have plenty of conservative Democrats who will break rank and vote with Republicans on various issues including women’s rights, immigration and climate change.

Here’s a recent example: Why 35 House Democrats Joined Republicans Against a Major Climate Policy

I don’t have much to add or suggest other than trying to get more progressives to win primaries. But even then sometimes we end up with people like Fetterman who ran as a progressive but now votes with Trump.