Especially during his 2008 campaign, as much as (or more so, parsing the details of his language) making specific, topical promises, Obama... "preached" and promised to be an advocate.

I think that as much as in specific deliverables, "the Left" feels rather thoroughly betrayed, on that front.

In this specific instance, he should have called Congress out on their behavior.

People understand real compromise. They also understand that when the other party is completely intractable, there comes a time when you confront them on this. Or you lose power.

Or... your original position was actually different from what you projected.