“Everything should be on the table,” West Virginia Sen. Joe Manchin declared Monday. He is a conservative Democrat, avid hunter and lifelong member of the National Rifle Association. Republican Sen. Chuck Grassley of Iowa proposed a debate not just about guns but also about mental issues.

White House officials said President Barack Obama would make preventing gun violence a second-term policy priority. But it was unclear what Obama would pursue or how, and aides said stricter gun laws would be only part of any effort.

The president met Monday afternoon with Vice President Joe Biden and a handful of Cabinet members to begin discussions on ways the country should respond to the Newtown shootings. Among those in attendance were Attorney General Eric Holder, Education Secretary Arne Duncan, and Health and Human Services Secretary Kathleen Sebelius.

It remains to be seen whether Obama and Congress can turn their rhetoric into action or whether the shock over the Connecticut shootings will fade before they do. Public opinion has shifted against tougher gun control in recent years, and the gun lobby is a powerful political force, particularly in Republican primaries. Also, Obama has called for a national dialogue after other mass shootings during his presidency, only to see those efforts take a backseat to other pressing issues.

This time, the president has vowed to use “whatever power this office holds” to safeguard the nation’s children against gun violence, suggesting he may put political muscle behind an assault weapons ban. He has long supported reinstating the ban, which expired in 2004, but never pressed for in his first term. Liberal Democrats on Capitol Hill are already laying the groundwork for legislation to outlaw the military-style arms.

Senate Majority Leader Harry Reid, D-Nev., vowed Congress would soon “engage in a meaningful conversation and thoughtful debate about how to change laws and culture that allow violence to grow.” The Senate Judiciary Committee will hold hearings on gun violence early next year.

Twenty children and six adults were killed when a gunman carrying a high-powered military-style rifle and other guns stormed Sandy Hook Elementary in Newtown, Conn., Friday morning.

Virginia’s Mark Warner, one of the few Senate Democrats who has found favor with gun rights groups, reversed course to back restrictions on assault weapons.

“The status quo is not acceptable anymore,” he said.

Since the shootings, the National Rifle Association has been silent. Requests for comments have gone unanswered, and officials are turning down interview requests until they have more details. Their 1.7 million-strong Facebook group has disappeared, and the group’s Twitter account — which is a favorite platform to communicate with supporters — has not sent a message since before the grim reality of Friday’s shootings set in.

At the White House, press secretary Jay Carney said stricter gun control laws were part of the solution but not the only one. He said the president would engage in “the coming weeks” in a process that includes input from law enforcement, mental health experts and lawmakers.

“It’s a complex problem that will require a complex solution,” Carney said. “No single piece of legislation, no single action will fully address the problem.”

Carney reiterated the president’s support for reinstating the assault weapons ban. Obama was outspoken in his calls for Washington to renew the ban during his 2008 White House run, but he made no effort to get it done during his first four years in office.

Sen. Dianne Feinstein, D-Calif., said she will introduce legislation next year to ban the sale of new assault weapons, as well as big clips, drums and strips of more than 10 bullets.

Police say the Newtown gunman, Adam Lanza, was carrying an arsenal of ammunition and used a high-powered rifle similar to the military’s M-16.

White House officials said the president feels some urgency to address gun violence in the wake of Friday’s violence. But Obama is not expected to take any formal action before the end of the year given the all-consuming efforts to resolve the “fiscal cliff” and nominate new Cabinet secretaries.

Some gun control advocates urged Obama and lawmakers to act quickly, while the sorrow and shock of the Newtown shooting is still raw.

“It demands immediate national action,” New York City Mayor Michael Bloomberg said. “It needs to be at the top of their agenda.”

The public has been split over tougher gun laws, and there is no early indication that the Newtown shootings are changing many minds. A Washington Post/ABC News poll conducted over the weekend showed 54 percent favor tougher laws, about the same as the 51 percent in favor earlier in the year. Seven in 10 are opposed to banning the sale of handguns to anyone except law enforcement officers, the highest percentage since 1999.

If Obama follows through on his pledge to make the stemming of gun violence a priority, he’s likely to press for a broad approach. He’s previously called for improving mental health services for young people and instituting more effective policing strategies, though his rhetoric has never turned into a policy push.

Obama has said he believes the Second Amendment guarantees an individual the right to bear arms and has spoken of a national heritage that cherishes hunting, shooting and the tradition of gun ownership. The president has signed laws letting people carry concealed weapons in national parks and in checked bags on Amtrak trains.