were unable to pass an assault weapons ban in the Democratically controlled Senate after the Sandy Hook Elementary School shooting.
First you say you wish to register all firearms. Conservatives and gun owners oppose this idea even more than they do an assault weapons ban. Even if by some miracle you managed to get this signed into law, a good number of gun owners would simply refuse to register their weapons. Some would decide to coat some of their firearms in Cosmoline, place them in PVC pipes and bury them in a hidden location. (I have talked to gun owners who have told me that they already had done this.)
When you passed a law to ban all firearms you would most likely have to cordon off neighborhoods and search every house. This would be very expensive and time consuming and it would be somewhat difficult to find people willing to risk their lives to take guns away from honest citizens. You might well start a revolution and/or some states would simply secede from the union. Even if you were successful you would manage to create far more violence and terrorist activities than we have today. This would outweigh any advantages of banning and confiscating all firearms.
That's why most thinking people who are gun control advocates tell gun owners, "Nobody is taking about taking your guns."