WASHINGTON — The Senate on Wednesday turned aside the latest effort by gun advocates to expand the rights of gun owners, narrowly voting down a provision that would have allowed gun owners with valid permits from one state to carry concealed weapons in other states.

A group comprising mostly Republicans, along with some influential Democrats, had tried to attach the gun amendment to the annual military authorization bill, a must-pass piece of legislation. But the provision got only 58 votes, two short of the 60 needed under Senate rules.

Two Republicans, SenatorsRichard G. Lugar of Indiana and George V. Voinovich of Ohio, joined with 35 Democrats and 2 independents to reject the amendment, which was bitterly opposed by a number of big-city mayors, includingMichael R. Bloomberg of New York.

The debate forced senators to wrestle with issues of states rights, sometimes in ways that seemed to clash with the general philosophies of their parties. Many Republicans, who typically favor limiting the ability of the federal government to dictate to states on social issues, voted in this case to limit the ability of states to insist on their own rules for concealed weapons carried by people from other states.

“Lives have been saved with the defeat of this amendment,” SenatorCharles E. Schumer, Democrat of New York and a leading opponent of the amendment, said in a statement. “The passage of this amendment would have done more to threaten the safety of New Yorkers than anything since the repeal of the assault weapons ban.”

The amendment was pushed by SenatorJohn Thune, Republican of South Dakota, and was co-sponsored by several Democrats from states where gun rights are broadly supported, like Montana, where SenatorsMax Baucus and Jon Tester both favored it. SenatorHarry Reid of Nevada, the majority leader, who is up for re-election in 2010, also supported the measure.

Going into Wednesday’s vote, supporters of gun rights seemed to have the momentum in the Senate, with a group of Democrats looking to block the amendment but acknowledging that the vote would be close. Under a parliamentary agreement, proponents needed 60 votes for passage.

This was the latest effort by gun advocates to push new firearms rights through Congress, where they hold increasing sway.

In May, Congress approved a measure that let gun owners with proper permits carry their loaded and concealed weapons in national parks. And Mr. Thune, SenatorTom Coburn, Republican of Oklahoma, and other pro-gun lawmakers had said they intended to bring more provisions seeking to expand gun rights to the Senate floor this year.

Every state except Illinois and Wisconsin allows concealed weapons, but the statutes concerning who is eligible to carry one vary widely by state. The amendment defeated Wednesday would have allowed gun owners with permits from states with looser restrictions to transport their guns to states with tougher restrictions; it would not have allowed the use of concealed weapons in Illinois and Wisconsin.

Critics of the amendment argued that it would undermine state and local gun-control laws, and accused Republican supporters, typically staunch defenders of states’ rights, of hypocrisy.

In their floor speeches and in the lead-up to the vote, Republicans repeatedly sought to rebut that accusation by saying that gun carriers would still have to obey state and local laws.

SenatorDavid Vitter, Republican of Louisiana, said the provision would not undermine local laws. He quoted a letter from a constituent who said she felt safer carrying her concealed weapon when she went out at night with her family.

“Specific state laws must be followed by the visiting individual,” Mr. Vitter said.

He also dismissed assertions that the provision would aid criminals.

Another Republican supporter of the amendment, Senator John Barrasso of Wyoming, said the law would make a gun permit “just like a driver’s license.”

“The Thune amendment is a license for self-defense across state lines,” Mr. Barrasso said.

Mayors Against Illegal Guns, a group of more than 400 mayors headlined by Mr. Bloomberg andThomas M. Menino of Boston, sent a letter to Mr. Reid and SpeakerNancy Pelosi of California pointing out that at least 31 states required gun owners to take a firearms training course to receive a permit and that at least 35 states banned those convicted of certain misdemeanors from carrying a concealed weapon.

“The vast majority of states have set minimum requirements for obtaining a permit to carry a concealed gun,” Mr. Bloomberg said in a statement, “and Congress should respect those laws instead of trying to usurp them.”