The Democratic party's ability to win elections by being only slightly better for the people than Republicans and still take the contributions from their oligarch masters is quickly coming to a halt. It is going to have to either make some drastic legislative attempts at making life better for working Americans or accept Republican rule for the next generation or so.
Their problem is that they picked the completely wrong guy for the job. Biden is a known neoliberal who looks to markets for answers to every problem we now face. He has Manchin as a sacrificial lamb at the moment to blame his lack of substantive progress on, but that doesn't explain his reversals on every major campaign promise, many of which he can do without approval from Congress.
It's very hard to campaign as the friend of the working stiff when Trump did more to support him/her than Biden did. Biden's first weeks in office were marked by a failure to deliver stimulus equal to what Trump promised and his promise to end student debt burdens for everyone was already out the window when he moved into the white house.
Progressives were told by establishment Democrats that Biden would become the "new FDR" if they simply kept pressure pushing him to the left. Stepping into that role is the only thing that will save him from being a one-term President, like his predecessor, but he doesn't have the character for anything more than a neoliberal sellout to the oligarchy.
That is what made him such natural for the nomination as leader of the new Democratic party. The only thing keeping the DNC alive enough to fog a mirror is the awfulness of the authoritarian Republican party. If a Republican with a smattering of charisma and able to feign compassion steps into the limelight to run Biden has zero chance at a second term. I know enough progressives who feel that the only hope we now have of surviving is to let it all fall in on itself to know that it is a thing.