Vice President Joe Biden acknowledged that new gun laws would not "fundamentally alter" the likelihood of another mass shooting, though he insisted there has been a "sea change" in American views on guns in the wake of Newtown.

"Nothing we're going to do is going to fundamentally alter or eliminate the possibility of another mass shooting or guarantee that we will bring gun deaths down to 1,000 a year from what it is now," Biden told reporters Thursday afternoon after he spent over an hour lunching with Democratic senators at the Capitol.

"But there are things that we can do, demonstrably can do, that have virtually zero impact on your Second Amendment right to own a weapon for both self defense and recreation that can save some lives," he said.

Biden was on the Hill to help sell a package of changes to the nation's gun laws that President Barack Obama is pushing in the wake of the Newtown, Conn., shootings that killed 20 elementary school children and six adults. The president wants an assault weapons ban, limits on the size of gun magazines, universal background checks and a federal gun trafficking statute.

The 1994 assault-weapons ban was allowed to expire in 2004, and there had been little appetite to reenact it.

Still, that was before Newtown -- and the vice president insisted Thursday that the tragedy there changed the public's attitudes toward gun-safety legislation, a reality that would make new firearms regulations possible.

"I'm not saying there's an absolute consensus on all these things," Biden said, "but there is a sea change, a sea change in the attitudes of the American people. I believe the American people will not understand -- and I know that everyone in that caucus understands -- they won't understand if we don't act.

"The visual image of those 20 innocent children being riddled with bullets has, has absolutely, not only traumatized the nation, but it has caused-- like the straw that broke the camel's back."

As evidence, he pointed to what he said was new support from evangelical Christian groups for some gun regulation. Biden told reporters that support from conservative religious groups that represent largely rural constituencies was different than it's been during past legislative fights over guns.

Biden said he did not watch a gun violence hearing the Senate Judiciary Committee held Thursday; at that hearing, Democrats and gun-violence victims clashed with Republicans and the National Rifle Association over whether universal background checks would reduce gun crimes.

Biden on Wednesday met with former Rep. Gabrielle Giffords and her husband, Mark Kelly, who both testified at the Senate hearing.