You've likely seen this post today on the subject of how genuine progressives can engage with a centrist Democratic president or presidential candidate.
Let me say right up that I am very much in agreement with Armando's analysis. But I have a few additional thoughts I would like to add.
When there is a system with multiple actors involved in the system, the system works best when each of the actors plays their role well and effectively.
Take our criminal justice system. It's based on an adversarial approach in which each of the participants has a role to play:
The judge rules on the law
The jury rules on the facts.
The prosecutor attempts to prove the defendant guilty
The Defense attorney attempts to cast doubt on that guilt.
In theory - and quite often in practice - if everyone plays their role well, the end result is justice.
There is an analogy to our political system.
The role of the official is to govern - which often requires compromise.
The role of the candidate is to get elected.
The role of the party is to elect and re-elect its candidates.
The role of the citizen is to vote in an informed way
And... The role of the advocacy group is to advocate - uncompromisingly - for the interests of those it represents.
And it is in that last that I claim there has been a failure in Democratic politics during recent years. Too many groups that ought to be playing the advocacy role have been confusing their role with that of the party. Too many groups like unions, environmental groups and others have come to see their role as electing and re-electing Democrats rather than advocating for the interests of those they represent. This has been largely driven by the sheer awfulness of the modern Republicans. It has created a dynamic in which too many on the "left" think they must give a free pass to any and all bad behavior by Democrats "because the Republicans are so much worse".
Compromise is part of the role of the office holder - it's integral to what they do. And, in the modern world, anyone who aspires to high office will be a triangulating centrist at best. But the way for progressives to move the compromise in a better direction is not to become slavish servants of the office holder. In order to move things our way, we must learn to be uncompromising advocates for our causes and our constituencies. We may - all to often - need to accept and help to elect less-than-ideal candidates. But once they are in office, our role is not to meekly prop them up. Our roles is to push them to be better - thereby giving them the political space to be the best they can be.