My basic thesis for the Democrats to win before they start running their mouths with desires, dreams, and all the rest - then have at it!
As I recall...Democrats won the last election. They have complete control Congress and the White House...should they choose to exercise it.

They have chosen instead to let Republicans determine which bills to vote for and which bills not to. As per the wishes of Manchin and Sinema.
Biden promised $15 an hour. He backed off that immediately and we will never hear another word of it. He promised a lot of things to progressive voters. He has already reneged on each and every one of them. M4A is DOA. Education and healthcare kicked to the side of the road. He is asking Republicans for permission before he does anything.

You said:
The Democrats are experiencing yet another attack of their progressive wing. This time they have decided to wreck the infrastructure thing by insisting that they have their way, in all things. Oh, and on the way, put another nail in the coffin of the Democratic party for next year.

It's okay if they wreck the infrastructure thing.
Like the ACA it doesn't go far enough. It's already too little and too late. It's another can kicked down the road. Another piece of legislation that will put money into corporate pockets and make the working guys' life a little harder.

If the left doesn't hold Democrat's toes to the fire who will...???

The Right that's who.

Is that what you really want?

Good coffee, good weed, and time on my hands...