Consider an alternate earth, where liberals responded to Obama's buget proposal by saying things like "“The vast majority of the Democratic base believes that Social Security is a non-negotiable plank,” and “If the President abandons Social Security, liberals will either sit the elections out completely, or move to create a third party. Either option puts Democrats on the path to a permanent minority.” Or “We respectfully warn Democratic Leadership that an abandonment of its principles will necessarily result in the abandonment of our constituents to their support,” or “If you bail out on this issue, I will leave the party and I will take as many people as I possibly can.” Not just Some Guy With A Blog (tm), but would be Presidential candidates and movers and shakers in the party.
Nice, but not going to happen, right? Except that it is happening, just with a different party.