If all that fails, Stockman said, he’d seek to impeach the president.

The United States has more firearms than any other nation – 270 million, according to the international Small Arms Survey, an independent research project at the Graduate Institute of International and Development Studies in Geneva. Background checks to purchase firearms have soared in the last month, after potential buyers became worried about possible new restrictions.

In a statement Wednesday, the politically powerful National Rifle Association accused the president of “attacking firearms and ignoring children.”

“The NRA will continue to focus on keeping our children safe and securing our schools, fixing our broken mental health system and prosecuting violent criminals to the fullest extent of the law,” the group said.

During his first term, Obama avoided the contentious subject of gun control, an issue that was unlikely to win him political points or bring him legislative success.

But since the Newtown massacre – which he describes as the worst day of his presidency – the president has embarked on a risky move. While he doesn’t have another election to worry about, he’s decided to spend political capital on gun control at the start of his second term, even as other hefty and controversial items beckon, including an immigration overhaul and a host of fiscal issues.

White House officials say the package of “common-sense proposals” is aimed at taking guns out of the hands of those who shouldn’t have them, getting “weapons of war” off the streets, making schools safer and offering more mental health services. The new proposals will cost an estimated $500 million. Administration officials said they didn’t know how many lives would be saved if the measures were enacted.

In addition to proposing legislation, Obama signed 23 executive actions that don’t need congressional approval. Some lawmakers complained that he was making an end run around them, though the actions are modest.

They include making it easier for federal and state agencies to make data available to the national background-check system, launching a national campaign for safe and responsible gun ownership, reviewing safety standards for gun locks and gun safes, and nominating a director to fill a years-long vacancy at the Bureau of Alcohol, Tobacco, Firearms and Explosives.

“As important as these steps are, they are in no way a substitute for action from members of Congress,” Obama said.

A Pew poll released this week showed mixed reactions to many of the president’s proposals. But Republicans, Democrats and independents overwhelmingly support background checks for private sales, preventing people with mental illness from buying guns and having more police officers in schools.

The recommendations came after Vice President Joe Biden spent the month after the Newtown shootings speaking to more than 200 organizations, including gun control groups, gun owners, religious leaders, law enforcement organizations, the medical community and child advocacy groups.

“No one can know for certain if this senseless act could have been prevented, but we all know we have a moral obligation . . . to do everything in our power to diminish the prospect that something like this could happen again,” Biden said.

Local officials and activists who’ve been waiting for years for presidential action touted the proposals.

Philadelphia Mayor Michael Anthony Nutter, the president of the U.S. Conference of Mayors, commended Obama for his “bold vision.” Dan Gross, the president of the Brady Center to Prevent Gun Violence, called Wednesday “a momentous day.”

New York Mayor Michael Bloomberg, perhaps the most visible champion of limiting access to guns – who hasn’t shied away from criticizing the president for not pushing the issue hard enough – said, “Today, it’s clear that the president and vice president heard us. . . . The vast majority of Americans support common-sense gun regulations, and clearly the White House was listening.”

Sandy Phillips, whose daughter, Jessica Redfield Ghawi, was among 12 people killed during the shooting spree in an Aurora, Colo., theater last summer, echoed the mayor’s sentiments after attending the White House event.

“It is the first time our politicians are caring and listening to us,” she said.

David Lightman and Maria Recio contributed to this report.