The Democratic-controlled Congress is moving to restore a Bush administration policy that allowed loaded guns in national parks.
The Senate voted Tuesday to allow guns in national parks and wildlife refuges, and the House could follow suit as soon as Wednesday.
The measure is included in a popular bill imposing new restrictions on credit card companies. Democratic leaders have said they hope to send a final version to the White House for the president's signature by week's end.
The Senate vote is a stark reversal from what many gun-control advocates expected when a federal judge blocked the Bush policy in March. The decision reinstated restrictions that had been in place since the Reagan administration. The rules severely restrict guns in the national parks, generally requiring them to be locked or stored.
The Obama administration accepted the March 19 ruling, saying that the Interior Department would review the policy over the next several months.
That timetable changed quickly last week after Oklahoma Sen. Tom Coburn inserted an amendment to the credit card bill that would allow concealed, loaded guns in parks and refuges.
To the surprise of many, the amendment easily passed, winning support from 67 senators — including 27 Democrats. Among those who voted "yes" was Senate Majority Leader Harry Reid of Nevada, who had blocked Coburn's amendment from coming to the Senate floor for more than a year. Seven other Western Democrats voted with Reid to support the Republican senator's amendment, which allows a range of firearms in national parks and wildlife refuges as long as they are allowed by federal, state and local law.
Spokesman Jim Manley said Reid is a strong supporter of the Second Amendment, adding that the guns in parks issue was a major concern for many Nevadans.
"The rules that apply to our federal lands are felt acutely in Nevada, where 87 percent of the state's land is managed by federal agencies," Manley said.
The Brady Campaign to Prevent Gun Violence, which sued to block the Bush policy, called the Senate vote reckless. The group called on President Barack Obama to demand that the gun provision be stripped from the credit card bill.
"Families should not have to stare down loaded AK-47s on nature hikes," said Brady campaign president Paul Helmke. "The president should not remain silent while Congress inserts reckless gun policies that he strongly opposes into a bill that has nothing whatsoever to do with guns."
Rep. Raul Grijalva, D-Ariz., chairman of a national parks subcommittee, said the measure would make parks more dangerous and urged House Democratic leaders to strip the amendment from the final bill.
Grijalva called the measure a "gotcha amendment" aimed at demonstrating the power of the National Rifle Association. Still, he acknowledged, it is likely to pass, given the pro-gun rights majorities in both the House and Senate.
"It's uphill. We know that," Grijalva said at a news conference Tuesday.
Democratic leaders said there was not enough time to send the bill to a House-Senate conference committee — where presumably it could be removed without a vote — and still get it to Obama by Memorial Day as he has requested.
Chris W. Cox, chief lobbyist for the NRA, called Grijalva's comments offbase.
"The National Rifle Association doesn't set the legislative calendar, and certainly doesn't determine which amendments are allowed to be offered or not offered in either the House or the Senate," he said.
Coburn said the gun measure protects every American's Second Amendment rights and also protects the rights of states to pass laws that apply to their entire state, including public lands.
"Visitors to national parks should have the right to defend themselves in accordance with the laws of their states," Coburn said.
House Democratic Leader Steny Hoyer, D-Md., told reporters on Tuesday that the House could vote separately on the gun legislation. Doing so would allow each measure to pass, but Democrats who endorse credit card reform could still vote as they wished on the gun measure.
If the two measures are passed separately as expected, they would be rejoined before being sent to the president as a single bill, Hoyer said.