Popular opinion was overwhelmingly against this action. Calls were ranging between 100:1 against and 300:1 against, depending upon representative. House Republicans rebelled against the Bush administration and its 19% approval rating; Democrats continued to be enablers. GOP economic conservatives who fought against this now have a reason to vote Republican.
I'm not paranoid enough to wonder whether the whole thing was a setup from the beginning - even though with a plan so disconnected from reality you have to wonder - but I do have to wonder if the House GOP saw the public reaction and took an opportunity handed to them.
eta: see kevin_standlee's commentary here about interesting parliamentary action. I wondered about some of that too but didn't know what it meant.
*: I am, for the record, pulling the "15-20" number completely out of my ass.