The proposal would overturn a 25-year-old regulation that has restricted loaded guns in national parks and wildlife refuges. The regulations require that guns be unloaded and placed somewhere that is not easily accessible, such as in a car trunk.
"The safety and protection of park and refuge visitors remains a top priority for the Department of the Interior," Kempthorne said in a statement.
The proposed rule change would incorporate current state laws authorizing the possession of concealed firearms "while continuing to maintain important provisions to ensure visitor safety and resource protection," he said.
Park rangers, retirees and conservation groups protested the plan, saying it will lead to confusion for visitors, rangers and other law enforcement agencies.
"This is purely and simply a politically driven effort to solve a problem that doesn't exist," said Bill Wade, chairman of the Coalition of National Park Service Retirees.
There is no data to suggest that the public would be served by allowing visitors to parks to possess concealed handguns, Wade and other critics said. They cited statistics showing that national parks are among the safest places in the country. The probability of becoming a victim of a violent crime in a national park is 1 in more than 708,000 - less likely than being struck by lightning, the groups said.
"This proposed regulation increases the risk to visitors, employees and wildlife rather than reducing it," Wade said.
Interior Department spokesman Chris Paolino said the rule change would give great weight to state and local laws. In Washington, D.C., for instance, which has a lot on national park land, guns would not be allowed since the city has banned handguns.
Sen. Dianne Feinstein, D-Calif., called the rule change confusing.
"This change makes no sense. It would create an incoherent, ineffective and inconsistent patchwork of policies," she said, noting that in some cases, rules would be different within the same national park. For example, Death Valley National Park is in both California and Nevada. California prohibits loaded and accessible weapons in state parks, while Nevada does not, Feinstein said.
"So which state law would apply at Death Valley National Park?" she said. "This sort of inconsistency would be an open invitation to poachers, would be almost impossible to enforce and would seriously place public safety at risk."
Paolino said that in a park that straddles more than one state, the law would differ depending on where a person was.
"When you are in the part of the park that allows concealed weapons and carry of those weapons within a state park, you will be allowed to do so in a national park," Paolino said. "When you cross the state boundary, those laws would change, depending on which state you venture into."
Kempthorne's announcement follows letters complaining about the gun restrictions from half the Senate - 41 Republicans and nine Democrats. The lawmakers called the existing guidelines confusing, burdensome and unnecessary.
The public has 60 days to comment on the new proposal, which was published Wednesday in the Federal Register.
