Have you been paying attention these last four years?
I have... but gun rights are a different order of magnitude in the minds of people who care about them. This isn't Obamacare, this is taking away people's guns. People care enough about this issue that if a law does get passed, they won't obey it, and in the meantime they will do their level best to end the political careers of the legislators that passed it.
There are a lot of single-issue voters on the 2nd Amendment. The fight this time around is an entirely different kettle of fish.