WASHINGTON — A working group led by Vice President Joe Biden is seriously considering measures backed by key law enforcement leaders that would require universal background checks for firearms buyers, track the movement and sale of weapons through a national database, strengthen mental health checks and stiffen penalties for carrying guns near schools or giving them to minors, administration sources said.

To sell such changes, the White House is developing strategies to work around the National Rifle Association that one source said could include rallying support from Walmart and other gun retailers for measures that would benefit their businesses. White House aides have also been in regular contact with advisers to New York Mayor Michael Bloomberg, a political independent and an outspoken gun-control advocate who could emerge as a powerful surrogate for the Obama administration’s agenda.

Biden’s group, formed last month after the massacre at a Newtown, Conn., elementary school that killed 20 children and six adults, plans to submit a package of recommendations to President Barack Obama this month. Once Obama’s proposals are set, he plans to lead a public relations offensive to generate popular support.

“They are very clearly committed to looking at this issue comprehensively,” said Dan Gross, president of the Brady Campaign to Prevent Gun Violence, who has been involved in the discussions. The proposals under consideration, he added, are “a deeper exploration than just the assault-weapons ban.”

The gun-control push is just one part of an ambitious political agenda that Obama has pledged to pursue after his decisive re-election victory in November, including comprehensive immigration reform, climate-change legislation and long-term deficit reduction. Obama also faces a reshuffling of his Cabinet and a looming debate over the nation’s debt ceiling that will compete for his time and attention in the coming months.

In addition to potential legislative proposals, Biden’s group has expanded its focus to include measures that would not need congressional approval and could be quickly implemented by executive action, according to interest-group leaders who have discussed options with Biden and key Cabinet secretaries. Possibilities include changes to federal mental-health programs and modernization of gun-tracking efforts by the Bureau of Alcohol, Tobacco, Firearms and Explosives.

“Simply coming up with one or two aspects of it really falls short of the magnitude of the gun issue in the country,” said Chuck Wexler, executive director of the Police Executive Research Forum.

Wexler was among a dozen law enforcement leaders who met with Biden and other administration leaders after the Dec. 14 massacre at Sandy Hook Elementary School in Newtown. The Dec. 20 summit included Attorney General Eric Holder Jr., Education Secretary Arne Duncan, Homeland Security Secretary Janet Napolitano, and Health and Human Services Secretary Kathleen Sebelius.

Biden “wanted to talk to us about the assault-weapons ban, automatic weapons, high-capacity magazines,” said Hennepin County (Minn.) Sheriff Richard Stanek, president of the Major County Sheriffs’ Association.

The vice president said the White House group would consider several proposals — from requiring background checks for all gun buyers to creating a new database that would allow the ATF to track all gun sales, according to participants.

Stanek said the meeting also included significant discussion of mental-health issues, violence in video games and movies, and the poor quality of information contained in databases used to conduct criminal background checks before issuing gun permits.

Some of the options the administration is considering may not ultimately be included in Obama’s package. A White House spokesman said Biden’s group was in the midst of its review and has made no decisions on its final recommendations.

The White House also is developing strategies to navigate the rocky and emotionally fraught terrain of gun politics once final policy decisions are made. The administration is quietly talking with a diverse array of interest groups, including religious leaders, mental health professionals and hunters, to build as broad a coalition as possible, those involved in the discussions said.

The president is expected to face fierce opposition from the NRA and its allies in Congress, including most Republicans and some Democrats.

But Biden signaled to those involved in the policy discussions said that the White House is not afraid of taking on the NRA, the nation’s largest gun-rights group.

NRA officials declined a request for comment. In response to the shooting in Newtown, Wayne LaPierre, the group’s executive vice president, called for installing armed police officers in every school.

“The only thing that stops a bad guy with a gun is a good guy with a gun,” LaPierre said at a news conference Dec. 21.

One potential strategy would be to win support for specific measures from interest groups that are normally aligned with the NRA, according to one person who works closely with the administration on gun-related issues and who spoke on the condition of anonymity because of the issue’s sensitivity.

For instance, this person suggested, Walmart and other major gun retailers may have an incentive to support closing a loophole that allows people to bypass background checks if they purchase firearms at gun shows or through other types of private sales. That could result in more people buying guns in retail stores.

Obama’s advisers have calculated that the longer they wait, the more distance there is from the Newtown massacre and the greater the risk that the bipartisan political will to tackle gun violence will dissipate.