NEW YORK — Democratic attorneys general from 17 states are calling on Congress to abandon legislation backed by the National Rifle Association that would allow concealed-carry gun permits issued in one state to be valid in all states.

The top prosecutors from states including New York, Pennsylvania, Iowa and California sent a letter to congressional leaders in both parties on Sunday warning that federal reciprocity proposals being debated on Capitol Hill “will lead to the death of police officers and civilians, the proliferation of gun traffickers, and acts of terrorism and other mass violence.”

“With the worst shooting in American history fresh in our memory, we urge you and your colleagues to reject these ill-conceived bills,” write the attorneys general in a letter organized by New York Attorney General Eric Schneiderman.

The fresh warning comes as the gun lobby, emboldened by complete Republican control of Washington, continues to press for looser gun restrictions in the weeks after an attack in Las Vegas that left 58 people dead and hundreds more wounded. It was the deadliest mass shooting in U.S. history.

Already, momentum appears to be slowing for a federal measure that would outlaw devices, known as “bump stocks,” that allowed the Las Vegas shooter’s semi-automatic weapons to mimic fully automatic guns. The National Rifle Association insists that the recent shooting has not softened its support for any its 2017 legislative priorities, which include legislation that would make it easier to buy gun silencers.

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The Concealed Carry Reciprocity Act of 2017, which already has more than 200 co-sponsors in the House of Representatives, “remains the NRA’s top legislative priority,” said Jennifer Baker, a spokeswoman for the NRA’s lobbying arm. The measure, if approved by Congress, would allow people with concealed-carry gun permits in one state to bring their guns into any other, regardless of whether that state has tougher requirements for obtaining permits.

Baker said the current “patchwork of state and local laws” creates confusion that “often leads to law-abiding gun owners running afoul of the law when they exercise their right to self-protection while traveling or temporarily living away from home.”

Supporters argue, for example, that the legislation would help protect truck drivers and women traveling across state lines alone at night.

Beyond the Democratic attorneys general, the critics also include gun control groups such as Everytown for Gun Safety, which is backed by billionaire former New York City Mayor Michael Bloomberg and vowed earlier in the year to spend “what it takes” to defeat the legislation.

An AP-GfK poll conducted last week found that 61 percent of Americans believe the nation’s gun laws should be more tough, while 27 percent want them to stay the same and another 11 percent want them less strict.

The answers were divided sharply along ideological lines. Nearly 9 in 10 Democrats, but just a third of Republicans, want to see gun laws made stricter.

The Democratic attorney generals argue that concealed-carry reciprocity would empower gun traffickers, terrorists and other criminals. And they say it would help criminals avoid permit requirements altogether should they assert residence in one of the 12 states that allow gun owners to carry a concealed weapon without a permit.

“After each tragedy we lament the loopholes in our federal gun laws. It’s vital that we not create another one,” Schneiderman said.

The letters’ authors also include attorneys general from Massachusetts, Oregon, Virginia, Rhode Island, Delaware, Hawaii, Illinois, Maryland, Connecticut, New Mexico, North Carolina and the District of Columbia.