"Assault weapons were developed for the U.S. military, not commercial gun manufacturers," said Lieberman, of Connecticut, who is retiring next month. "This is a moment to start a very serious national conversation about violence in our society, particularly about these acts of mass violence."
Gun rights activists remained largely quiet, all but one declining to appear on the Sunday talk shows. In an interview on "Fox News Sunday," Rep. Louie Gohmert, a Texas Republican, defended the sale of assault weapons and said that the principal at Sandy Hook, who authorities say died trying to overtake the shooter, should herself have been armed.
Contributing to this report were Associated Press writers John Christoffersen, Ben Feller, Adam Geller, Jim Kuhnhenn and Michael Melia in Newtown; David Collins in Hartford, Conn.; Brian Skoloff in Phoenix; and Anne Flaherty in Washington.