BALTIMORE – Democratic governors and lawmakers in at least 10 U.S. states are seeking new restrictions on guns and ammunition after last month’s school shooting in Connecticut, challenging the firearms lobby’s political clout.

New York Gov. Andrew Cuomo, D, last week called for making his state’s gun laws the toughest in the nation with restrictions that include a ban on sales of high- capacity ammunition magazines. Colorado Gov. John Hickenlooper, D, wants background checks on private gun sales.

The proposals mark a shift from previous years, when debate focused on expanding residents’ right to carry guns, including at colleges or in public buildings. The Dec. 14 shooting at Sandy Hook Elementary School in Newtown, Conn., which killed 20 children and 6 adults, is fueling calls for action.

“The main thrust has been on expanding gun rights, not a retraction,” said Richard Feldman, president of the Independent Firearm Owners Association, a Rindge, N.H.-based group that opposes restrictions on gun owners. “This is the most intense discussion of the gun issue in my lifetime.”

Vice President Joe Biden said last week there’s a growing agreement on the need for background checks on all types of gun sales and a ban on high-capacity magazines. Biden said he plans to deliver by tomorrow recommendations for legislative and executive actions to stop gun violence as part of the administration’s response to the Connecticut shooting.

The National Rifle Association, the nation’s largest gun- rights group with 4 million members, said last week the Obama administration is moving to “attack the Second Amendment,” which protects the rights of Americans to bear arms. The Fairfax, Va.-based group’s opposition poses an obstacle in the House, which is controlled by Republicans, who more often side with gun-rights advocates than Democrats.

Other states in which governors or lawmakers are calling for new restrictions include Arizona, California, Connecticut, Delaware, Florida, Illinois, Maryland and Oregon.

More proposals may emerge as legislative sessions in many states begin in coming weeks. In a recent letter to supporters, the NRA said state lawmakers “will soon be voting on dozens of new bills to impose greater restrictions on your right to own and use firearms.” Andrew Arulanandam, a spokesman for the group, didn’t respond to a telephone message seeking comment on the proposals.

Cerberus Capital Management, the New York-based owner of Freedom Group, the largest U.S. gunmaker, said last month that it isn’t taking a position on gun-control debates and is moving to sell the company. Peter Duda, a spokesman for Cerberus at Weber Shandwick, a public relations firm, declined to comment further.

Republicans control a majority of governorships and state legislatures. Gun-control measures will be more difficult to pass in those states, said Andy Pelosi, the executive director of States United to Prevent Gun Violence, a New York-based firearms-control group.

“We’re going to have to fight a very uphill battle, whether it’s in Washington or state legislatures,” he said.

Maryland Gov. Martin O’Malley, D, said Monday that he plans to propose limits on assault weapons and high- capacity magazines, as well as tougher licensing requirements for handguns. He predicted the measures will win approval.

“We know that it makes absolutely no sense, when you look at the level of carnage on our streets from guns, to blame everything but guns,” he said in a speech at Johns Hopkins Bloomberg School of Public Health in Baltimore at the start of an academic conference on gun violence.

New York’s Cuomo produced the most sweeping proposal. In Albany on Jan. 9, he said he wants to close loopholes in the state’s assault weapon ban, forbid large-capacity magazines and allow the state to revoke gun licenses and confiscate weapons.

The next day, Colorado’s governor called for background checks on all gun sales, not just those purchased at retail stores or at gun shows. In Arizona, a Democratic state senator is seeking to force the same step.

“The governor generally opposes efforts that would infringe on the rights of lawful gun owners,” said Matthew Benson, a spokesman for Arizona Gov. Jan Brewer, R.

In California, a Democratic state senator proposed requiring permits and background checks to buy ammunition. In Florida, a state House Democrat’s bill would allow for limits on carrying concealed weapons and ammunition on public property.

The Democratic governors of Maryland, Connecticut and Delaware are preparing their own proposals for restrictions.

In Oregon, Gov. John Kitzhaber, D, is awaiting recommendations of his staff and favors banning assault weapons, said Tim Raphael, a spokesman.

“The governor really sees no reasons for citizens to own assault weapons,” Raphael said.

In Illinois, Gov. Pat Quinn, D, supports a ban on assault weapons, said a spokeswoman, Brooke Anderson. A similar measure failed to advance in the legislature last year after opposition from gun groups, including the NRA.

Richard Pearson, executive director of the Illinois State Rifle Association, which opposed the bill, said he’s poised for a fight when it’s revived in the legislature this year.

“It’s going to be a long and tough fight,” he said.

Since the Connecticut shooting, many state Republican leaders have responded by calling for improvements in mental- health programs and school safety, not curbs on guns.

Louisiana Gov. Bobby Jindal, R, ordered a commission to scrutinize safety in schools. In South Carolina, a Republican lawmaker is seeking to allow teachers to carry concealed weapons into school. In Texas, Lt. Gov. David Dewhurst, R, said he’s in favor of funding firearms training for school teachers or administrators.

In Ohio, the week after the Connecticut shooting, Gov. John Kasich, R, signed a law allowing concealed weapons in state-owned parking garages. He said the response shouldn’t be to erode gun owners’ rights and instead moved to spend $5 million to help families deal with mental illness.

“We can’t do everything and this isn’t going to solve everything, but it’s at least I think a good start,” he told reporters this month.