Reaction to the massacre at the Sandy Hook Elementary School in Newtown, Conn., on Friday could be a tipping point for America, including political leaders in Washington. The horror of a gunman killing 20 first-graders and six adults in a spray of bullets from an assault rifle might do what other recent mass shootings, including the theater shooting in Aurora, Colo., failed to do — force a national conversation about guns, the role of culture, sensible gun regulations and how improved mental health treatment could reduce killings.

All parties in the national conversation should admit that no specific action can eliminate violent behavior and acts of cruelty upon innocent victims. But the national mood this week in the United States is mostly one of frustration and resolve, with Americans concluding that something must be done.

It’s no longer acceptable for politicians to merely make somber speeches following increasingly frequent killings, talking only about healing and praying for victims and their families.

Accepting the limits of whatever changes are considered, a national discussion about the frequency and shocking tolls taken in these mass shootings is overdue. And it must be a discussion, not a political debate with the familiar hotheaded partisans talking past one another.

The usual pro-gun and anti-gun or pro-regulation positions should be abandoned in favor of finding common ground and common-sense solutions. The discussion doubtless will focus on possible legislation, but it should also include reflection on what many see as a culture of violence in the United States.

Most people understand that Congress cannot legislate the solution; there is no single answer.

The discussion also should look at mental health treatment and how potential mass killers can be detected and helped before they act.

The first step should be to limit the killing capacity of some weapons without curtailing the rights of hunters or individuals to possess firearms to protect themselves.

A return of the 1994 ban on assault weapons and high-capacity clips that was allowed to lapse in 2004 is gaining support in Congress. On Monday, Sen. Joe Manchin, D-W.Va., an avid hunter and lifetime member of the National Rifle Association, said “I don’t know anyone in the sporting or hunting arena that goes out with an assault rifle; I don’t know anyone who needs 30 rounds in a clip to go hunting.” The vast majority of responsible hunters would agree.

A logical second step would involve closing the loophole for background checks for firearms sales by private sellers, which usually means gun-show sales. It is estimated that 40 percent of gun sales today do not involve a background check, proving that the gun-show loophole must be closed.

In his moving speech at Newtown, President Barack Obama vowed to use the power of the presidency to do something to make Americans safer from gun violence. While a few members of Congress are stepping forward on the issue, the expectation is for the president to lead, instead of repeating his inaction following the mass shooting in the theater in Aurora, Colo.

New York City Mayor Michael Bloomberg is putting pressure on Obama, saying “He’s the commander in chief, not the consoler in chief.”

The shock of young children being gunned down with an assault rifle has stunned America and the world. Parents especially can feel the emotions Obama expressed in his somber speech in Newtown.

Now, Americans expect more than talk. They expect action. But even the most passionate gun-control advocates cannot ignore the fact that the problem is not limited to guns; the national conversation has to talk about violence in today’s popular culture and mental health treatment.

Conceding that there is no easy solution does not mean that doing nothing is acceptable. It isn’t.

It’s past time to do something.