President Obama on Wednesday tapped Vice President Biden to lead an administration-wide effort looking at gun control and other measures in the wake of the Connecticut school shooting last week.

"The fact that this problem is complex can no longer be an excuse for doing nothing," Obama said.

The move marks the first concrete step by the White House toward crafting new firearms restrictions. The president did not announce any major policy decisions on Wednesday, but said the task force of Cabinet officials and outside organizations led by Biden would submit legislative proposals to him no later than January.

Some lawmakers, in the wake of the tragedy, have called for a broad-based response, looking at everything from mental health to school security to American culture. Sen. Joe Lieberman, I-Conn., in a call soon joined by others, proposed a national commission examining the entertainment industry and particularly video games.

Obama and top administration officials suggest the response to the Newtown, Conn., mass murder could include a range of recommendations. But the focus, given the debate that has accelerated on Capitol Hill in recent days, is likely to be gun control.

The president said Wednesday that he chose Biden to lead the task force in part because of his role in crafting the 1994 assault-weapons ban. Obama spoke favorably of the ban, as well as proposals to strengthen background checks and ban high-capacity magazines. The president tried to walk a line between assuring Americans that gun rights would largely be protected, while making the case for some new restrictions.

"The fact is the vast majority of gun owners in America are responsible," he said. "But you know what -- I am also betting that the majority, the vast majority of responsible law-abiding gun owners would be some of the first to say that we should be able to keep an irresponsible law-breaking few from buying a weapon of war."

Obama said he would use "all the powers" of his office to prevent more tragedies. "We won't prevent them all, but that can't be an excuse not to try," he said.

Attorney General Eric Holder said Wednesday that the administration will craft proposals for Congress to consider over the next few weeks. He said a "strong" Bureau of Alcohol, Tobacco, Firearms and Explosives is also important.

White House Press Secretary Jay Carney said Tuesday that Obama is "actively supportive" of Sen. Dianne Feinstein's, D-Calif., push to bring back the assault-weapons ban. He also said the president supports closing the so-called gun show loophole.

Gun-rights advocates have started to push back on the swift call for more firearms regulation. The National Rifle Association, after remaining silent in the immediate aftermath of the tragedy, released its first -- albeit brief -- statement on Tuesday, and announced it would be holding a major press conference on Friday.

The White House sees some urgency in formulating a policy response to the shooting, even as Obama and his top aides are consumed with averting the looming fiscal crisis before tax hikes and spending cuts take effect in January.

As many pro-gun lawmakers have called for a greater focus on mental health issues and the impact of violent entertainment, aides say Obama also prefers a holistic approach.

"It's a complex problem that requires more than one solution," Carney said Tuesday. "It calls for not only re-examining our gun laws and how well we enforce them, but also for engaging mental health professionals, law-enforcement officials, educators, parents and communities to find those solutions."

Still, much of the immediate focus after the shooting is on gun control, an issue that has been dormant in Washington for years. Obama expended little political capital on gun issues during his first term, despite several mass shootings, including a movie theater attack in Aurora, Colorado, in the midst of this year's presidential campaign.

The White House has begun to signal that Obama may be more proactive on gun issues following the murders of the elementary school youngsters, ages 6 and 7.

The policy process Obama announced Wednesday was expected to include input from the departments of Justice, Education, and Health and Human Services. The heads of those agencies met with Obama at the White House on Monday.

Fox News' Ed Henry and The Associated Press contributed to this report.