Washington - President Obama declared on Wednesday that he would make gun control a "central issue" as he opens his second term, promising to submit broad new firearm proposals to Congress no later than January and to employ the full power of his office to overcome deep-seated political resistance.
Leading House Republicans responded to the president's pledge in the aftermath of the Connecticut school massacre by restating their firm opposition to new limits on guns or ammunition, setting up the possibility of a bitter legislative battle and a philosophical clash over the Second Amendment soon after Mr. Obama's inauguration.
Having avoided a politically difficult debate over guns for four years, Mr. Obama vowed to restart a national conversation about their role in American society, the need for better access to mental health services and the impact of exceedingly violent images in the nation's culture.
He warned that the conversation — which has produced little serious change after previous mass shootings — will be a short one, followed by specific legislative proposals that he intends to campaign for, starting with his State of the Union address next month.
"This time, the words need to lead to action," Mr. Obama said. "I will use all the powers of this office to help advance efforts aimed at preventing more tragedies like this."
At an appearance in the White House briefing room, the president said that he had directed Vice President Joseph R. Biden Jr. to lead an interagency effort to develop what the White House said would be a multifaceted approach to preventing mass shootings like the one in Newtown, Conn., last week and the many other gun deaths that occur each year.
As evidence of the brutal cost of gun violence, Mr. Obama said that since Friday's school shooting in Connecticut, guns had led to the deaths of police officers in Memphis and Topeka, Kan.; a woman in Las Vegas; three people in an Alabama hospital; and a 4-year-old in a drive-by shooting in Missouri. They are, he said, victims of "violence that we cannot accept as routine."
Accompanied by Mr. Biden, the president signaled his support for new limits on high-capacity clips and assault weapons, as well as a desire to close regulatory loopholes affecting gun shows. He promised to confront the broad pro-gun sentiment in Congress that has for years blocked gun control measures.
That opposition shows little signs of fading away. While the death of 20 children at Sandy Hook Elementary School on Friday appears to have persuaded some Democratic lawmakers to support new gun control measures, there has been little indication that Republicans who control the House — and are in a standoff with Mr. Obama over taxes — are willing to accept such restrictions.
House Democrats urged Speaker John A. Boehner on Wednesday to bring a ban on high-capacity ammunition magazines to a vote by Saturday — a step he is highly unlikely to take.
Representative Jim Jordan, Republican of Ohio, an influential conservative leader, said in a statement that "it is clear that criminals will always find ways to acquire weapons and use them to commit acts of violence."
"Passing more restrictions on law-abiding citizens will not deter this type of crime," he said.
Mr. Jordan and other House Republicans declined to be interviewed, saying through aides that it was time to mourn, not to debate policy.
"There will be plenty of time to have this conversation," said Brittany Lesser, a spokeswoman for Representative Steve King, Republican of Iowa, "but it is not amidst the funerals of these brave young children and adults."
This week, Mr. King told an Iowa radio station, KSCJ, that "political opportunists didn't wait 24 hours before they decided they were going to go after some kind of a gun ban." He also expressed doubt about gun control measures, saying, "We all had our cap pistols when I was growing up, and that didn't seem to cause mass murders in the street."
Representative Howard Coble, Republican of North Carolina, said in an interview that he thought the talk of gun control was "probably a rush to judgment" that missed the real issue.
"I think it's more of a mental health problem than a gun problem right now," he said. "Traditionally states that enact rigid, inflexible gun laws do not show a corresponding diminishment in crime."
While Mr. Coble said he would want to study any proposal made by the president, he said fellow Republicans on the Judiciary Committee, which would consider any gun recommendations, probably agree with his views.
One senior Republican, Representative F. James Sensenbrenner Jr. of Wisconsin, signaled an openness to review Mr. Obama's proposals.
"As the president said, no set of laws will prevent every future horrific act of violence or eliminate evil from our society, but we can do better," Mr. Sensenbrenner said in an e-mailed response to questions.
Mr. Sensenbrenner noted that he had co-sponsored the Brady gun control bill in the 1990s. "Our country must also grapple with difficult questions about the identification and care of individuals with mental illnesses," he said.
On Wednesday the president said that Mr. Biden's group would propose new laws and actions in January, and that those would be "proposals that I then intend to push without delay." Mr. Obama said Mr. Biden's effort was "not some Washington commission" that would take six months and produce a report that was shelved.
"I urge the new Congress to hold votes on these new measures next year, in a timely manner," Mr. Obama said.
White House aides said Mr. Biden would meet with law enforcement officials from across the country on Thursday, along with cabinet officials from the departments of Justice, Homeland Security, Education and Health and Human Services.
Mayor Michael R. Bloomberg of New York praised Mr. Obama's announcement and said he offered his "full support" to Mr. Biden in a phone conversation on Wednesday. But Mr. Bloomberg, a vocal advocate of tougher gun control, also urged the president to take executive actions in the meantime, including making a recess appointment of a new director for the Bureau of Alcohol, Tobacco, Firearms and Explosives. Republicans have blocked an appointment to the post for years.
"The country needs his leadership if we are going to reduce the daily bloodshed from gun violence that we have seen for too long," Mr. Bloomberg said of Mr. Obama.
Gun control advocates have urged the White House and lawmakers to move rapidly to enact new gun control measures before the killings in Connecticut fade from the public's consciousness. Senator Dianne Feinstein, Democrat of California, has said she intends to introduce a new ban on assault weapons and high-capacity magazines on the first day of the next Congress in January.
During his first term, Mr. Obama largely avoided the issue of gun control, even as high-powered firearms were used in several mass shootings. Asked bluntly about his lack of past action on the issue, the president appeared irritated, citing the economic crisis, the collapse of the auto industry and two wars as matters that demanded attention.
"I don't think I've been on vacation," he said curtly.
He then conceded, "All of us have to do some reflection on how we prioritize what we do here in Washington."
Peter Baker contributed reporting.