Regardless of what path Mr. Obama chooses to pursue, much depends on Congress's will to implement the administration's plan -- and the White House faces an uphill battle in overcoming immense pushback from powerful pro-gun lobbies, as well as longstanding Republican opposition to any tightening of gun laws. One possibility for sidestepping congressional opposition, Biden suggested yesterday, is that the president advance his agenda through executive order rather than pushing legislation through the House and Senate. It's unclear, however, how much Mr. Obama might be able to accomplish through that means.

A number of public officials -- including Bloomberg and former Rep. Gabby Giffords, D-Ariz., herself a victim of gun violence -- have also launched campaigns aimed at building public support for what they say are common-sense solutions for reducing gun violence. And new evidence suggests that support is growing: According to a December CBS News poll showed, 57 percent of Americans believe gun laws should be made more strict.

But the NRA, the most powerful of the pro-gun groups, is promising to pose staunch opposition to any such laws.

In the meantime, the vice president is urging both sides to seek common ground amid the fraught political debate.

"I'm not sure we can guarantee that this will never happen again. But as the president said, even if what we do only saves one life, it makes sense," he said. "And I think we can do a great deal without in any way imposing on or impinging on the rights of the second amendment, that the second amendment guarantees. That's what this is all about."