A group of more than 70 lawmakers pressed President Obama on Wednesday to block drilling off the Atlantic and Alaskan coasts "forever" by using unilateral authority under the law that makes such a decision irreversible by the next president.

"Protecting the Atlantic and Arctic coastlines against future oil and gas extraction would send a powerful signal to the world that the United States is fully committed to delivering on our climate commitments," a letter from the lawmakers said. "It would help defend our communities and future generations against the health, environmental and economic impacts of climate change and the possibility of a catastrophic oil spill."

The letter signed by 74 lawmakers was led by Reps. Jared Huffman, D-Calif, and Frank Pallone Jr., D-N.J., who serves a ranking member of the House Energy and Commerce Committee. Rep. Frank LoBiondo of New Jersey was the only Republican to sign the letter that asked Obama to "fully withdraw" from including offshore drilling on the Atlantic and the Arctic coastlines from the administration's final five-year offshore energy plan due out by the end of the year.

But the lawmakers want Obama to take a bolder step in blocking the lease sales from going forward no matter what offshore areas the Interior Department's plan designates.

They recommend that the president use his "unilateral authority" to block drilling in the Arctic and the Atlantic in perpetuity. "You and your predecessors have used section 12(a) [under the Outer Continental Shelf Lands Act] to protect hundreds of millions of marine acres, some for defined time periods and others in perpetuity," the letter said. "Notably absent from section 12(a) is authority for a successor president to undo a permanent withdrawal.

"We believe that forever withdrawing the Arctic and the Atlantic oceans from leasing, reflecting the strong public interest in stemming climate change and protecting our coasts, is a particularly appropriate use of the statute's broad and clear terms," the letter added.

The Interior Department included drilling off the Atlantic coast in an early version of the five-year plan. But its latest proposal reversed course and rejected allowing lease sales off the eastern seaboard for the first time in the history of the agency's offshore drilling program. However, it kept drilling in the Arctic open, but said problems in the oil market are making it uneconomical for companies to drill there anyway.

Environmentalists have pressed the administration almost daily to remove the lease program in the Arctic and not reverse its decision on the Atlantic seaboard when it finalizes the five-year plan.

The oil and gas industry has been lobbying the administration to include the Atlantic in the final plan and not to reverse its lease proposal for the Arctic.