Vice President Joseph R. Biden Jr. joined Mayor Michael R. Bloomberg and some families of the victims in the Connecticut school shootings on Thursday to push for new federal gun laws, just days after Senate Democrats dropped an assault weapons ban from a gun-regulation package they plan to consider next month.

Mr. Biden urged lawmakers to “think about Newtown,” the site of the shootings, as they considered stricter gun regulations.

“For all those who say we shouldn’t and can’t ban assault weapons, for all those who say the politics are too hard, how can they say that?” Mr. Biden said at a news conference in the Blue Room at City Hall. “You take a look at those 20 beautiful babies, and what happened, and those 6 teachers and administrators.”

Many gun-control advocates had made bans of military-style assault weapons and high-capacity ammunition magazines the centerpieces of their legislative agendas in the aftermath of the Dec. 14 school shootings at Sandy Hook Elementary. The gunman, Adam Lanza, carried high-capacity ammunition magazines and used a military-style assault weapon to fatally shoot 20 first graders and 6 adults at the school, before he killed himself.