The sense of betrayal Chocolo describes among many then-freshman Republican congressmen is very real. They feel they were tricked by establishment Washington into voting for fake spending cuts back in 2011 and now they want to make those cuts real in 2013. Democratic plans to replace these very real cuts with tax hikes are completely out of the question, and kicking the can down the road by back-loading the cuts is now also suspect.
If the sequester is undone, it will have to be done with Democratic votes in the House. And the only way that happens, is if at least part of the cuts are replaced with tax hikes. That isn’t happening either. Which is why the sequester is almost certainly going to happen on schedule.