The Connecticut shootings reignited calls from gun control activists and some elected officials for laws restricting access to weapons.
A crowd of about 200 people gathered outside the White House on Friday evening for a candlelight vigil, many of them drawn together through social media sites. A few held signs that read, "Mr. President, we are praying for your action."
The Rev. Michael McBride of Oakland, Calif., in Washington as part of a religious-based effort to speak out against gun violence, called on President Barack Obama to take a stand for gun control before his State of the Union address or during it.
"Platitudes and condolences do not help. We need action," McBride said.
In New York, Mayor Michael Bloomberg said it is time to move forward with serious gun laws.
"We have heard all the rhetoric before," said Bloomberg, who is a leader of a group of mayors against illegal gun ownership. "What we have not seen is leadership — not from the White House and not from Congress. That must end today."
Rep. Carolyn McCarthy, D-N.Y., whose husband was one of six people killed in a shooting on the Long Island Rail Road in 1993, said she will resume her quest for broad gun violence legislation: reinstating the assault weapons ban that expired in 2004; banning high-capacity magazines; requiring criminal background checks on gun buyers at gun shows; and improving instant background checks to more thoroughly catch people with histories of mental illness.
"I'm not going to be shy anymore," she said.
As the debate over gun control flares anew, it is likely to focus on the types of guns that were found with the suspect in Connecticut, a Glock pistol and a Bushmaster .223 M4 carbine rifle, which are similar in type to the weapons used in mass shootings in Oregon and Colorado. Both guns are popular for target shooting and self-defense, and both have been singled out by gun control advocates because of their ability to rapidly fire multiple rounds and accommodate large magazines.
But Republicans said tighter gun control measures would be the wrong step.
"That's one thing I hope doesn't happen," said Rep. Mike Rogers, a senior Michigan Republican who is a former FBI agent. "That's certainly the lowest common denominator. What is the more realistic discussion is, how do we target people with mental illness who use firearms?"
Kristen Rand, the legislative director of the Violence Policy Center, a gun control advocacy group, said it is too early to say whether the Newtown, Conn., massacre will yield different political results than previous mass shootings. But she said she believes it will for two reasons: the victims were children, which has elicited a gut-wrenching response across the country, and the National Rifle Association proved to be a political paper tiger in the 2012 election.
David Chipman, a former special agent at the Bureau of Alcohol, Tobacco and Firearms who is now a consultant to Mayors Against Illegal Guns, said he believes the shooting is "a game changer."
President Barack Obama advocated tougher gun laws after the shooting in Aurora on July 20, but he did not break new ground in proposing legislation, and he reaffirmed his belief in the constitutional rights of gun owners. In a speech to the National Urban League in New Orleans, Obama endorsed tighter restrictions to bar mentally unstable people from purchasing weapons. Officials say the dead suspect in the Newtown massacre suffered from personality disorders.
"These steps shouldn't be controversial," Obama said then. "They should be common sense."