Updated

The Obama administration is going to bat for former President Bush by defending his last-minute rule allowing loaded guns in national parks.

The Washington Post reported Tuesday that while the Interior Department is internally reviewing whether the measure passes environmental muster, the Justice Department sought to block a preliminary injunction of the controversial rule in response to a lawsuit filed Friday by gun-control and environmental groups.

The regulation took effect Jan. 9 and allows visitors to bring concealed, loaded guns into national parks and wildlife refuges. For more than 20 years, they were allowed in such areas only if they were unloaded or stored and dismantled.

The three groups fighting to overturn the rule are the Brady Campaign to Prevent Gun Violence, the National Parks Conservation Association and the Coalition of National Park Service Retirees. They contend that the Bush administration violated several laws in issuing the rule, such as failing to conduct a sufficient environmental review under the National Environmental Policy Act. They also claim that the new policy could discourage some visitors from visiting national landmarks.

But the Justice Department said in its reply that the new rule "does not alter the environmental status quo, and will not have any significant impacts on public health and safety."

Interior Secretary Ken Salazar has requested an internal assessment of whether the measure has any environmental impacts the government needs to take into account, an Interior spokesman told the newspaper Monday.

Click here to read the Washington Post report.