WASHINGTON — President Obama announced Wednesday that his administration will approve significant oil and gas exploration off America’s coasts.

The move, which includes a possible sale two years from now of leases off the Virginia shore, ends a long-standing moratorium on oil and gas drilling along much of the East Coast, from Delaware to central Florida.

In a speech on energy security, Obama said he was steering a course between staunch opposition to any new offshore drilling and advocacy of opening all U.S. waters to energy exploration without restriction.

The compromise, which Obama said has been under consideration for more than a year, split environmentalists, with some applauding the administration’s moderation and others questioning its precedent-setting decision. Republican critics welcomed the expansion of offshore exploration but complained that it did not go far enough.

“Given our energy needs, in order to sustain economic growth and produce jobs and keep our businesses competitive, we’re going to need to harness traditional sources of fuel even as we ramp up production of new sources of renewable, home-grown energy,” Obama said. “So today we’re announcing the expansion of offshore oil and gas exploration — but in ways that balance the need to harness domestic energy resources and the need to protect America’s natural resources.”

Obama made the remarks in an appearance with Interior Secretary Ken Salazar at Joint Base Andrews Naval Air Facility Washington, formerly Andrews Air Force Base. He spoke against the backdrop of a new fighter jet and a light armored vehicle that the military has been testing to run on a mixture of biofuels.

The new strategy calls for oil and gas exploration in the eastern Gulf of Mexico, more than 125 miles from Florida’s coast, and in large areas in the Chukchi and Beaufort seas in the Arctic Ocean, north of Alaska, after the government conducts detailed studies.

However, the administration will continue to bar exploration in Alaska’s Bristol Bay, which is a critical wildlife habitat, and it canceled several lease sales in the Chukchi and Beaufort seas that had been planned under the Bush administration.

Obama pledged that new technologies would be employed to reduce the impact of oil exploration. “We’ll protect areas vital to tourism, the environment and our national security,” he said. “And we’ll be guided not by political ideology, but by scientific evidence.”

He said his announcement “is part of a broader strategy that will move us from an economy that runs on fossil fuels and foreign oil to one that relies more on home-grown fuels and clean energy.”

Obama called on the nation to “move beyond the tired debates between right and left, between business leaders and environmentalists, between those who would claim drilling is a cure-all and those who would claim it has no place.”

The exploration plan, which Salazar called “a new direction” for energy policy, reflects the administration’s effort to drum up support for comprehensive energy and climate legislation by making concessions to those who want expanded domestic energy production. According to several sources, the administration is hoping to appeal to such key senators as Democrat Mark Begich and Republican Lisa Murkowski of Alaska, as well as Mary Landrieu, D-La.

In a joint statement, Murkowski and Begich welcomed Obama’s plan and urged the administration “to continue to fund environmental studies in the North Aleutian Basin so that a more informed decision can be made about possible development in the future.”

Joshua Freed, who directs the Clean Energy Initiative at the centrist think tank Third Way, said, “It’s good optics to get ahead of the coming high summer gas prices, but it’s going to be tough to get skeptical senators on board” for a bill being drafted by Sens. John Kerry, D-Mass., Lindsey Graham, R-S.C., and Joe Lieberman, I-Conn.

Graham issued a statement calling the announcement “a good first step.”

But many Republicans criticized Obama’s initiative as a half-hearted measure. House Republican Conference Chairman Mike Pence, R-Ind., called the move “a smokescreen,” saying that “only in Washington, D.C., can you ban more areas to oil and gas exploration than you open up, delay the date of your new leases and claim you’re going to increase production.”

Rep. Eric Cantor, R-Va., the House minority whip, said he was “encouraged” that Obama has endorsed energy exploration off his home state’s coast, which he said would create jobs for Virginians and reduce reliance on foreign oil.

Cantor said the moratorium on offshore drilling should be lifted “on not just the East Coast, but in the Gulf of Mexico, the Pacific Coast and in Arctic Alaska as well.” And he complained that Obama continues “to keep a job-killing cap-and-trade energy tax on the table.”

Marilyn Heiman, the Pew Environment Group’s U.S. Arctic program director, lauded the administration’s decision to ban drilling in Bristol Bay. The bay is “the home of the world’s largest wild sockeye salmon run and the nursery for Bering Sea fisheries that provide 40 percent of our nation’s seafood,” she said. “With fish stocks declining around the globe, we cannot afford to put Bristol Bay’s vibrant fisheries at risk.”

Charging that Obama’s plan “continues our reliance on dirty fossil fuels,” Maggie L. Fox, president of the Alliance for Climate Protection, said: “We cannot simply drill our way to energy security.”

The strategy that Obama and Salazar announced will guide both the current 2007-2012 offshore oil and gas leasing program authored by George W. Bush’s administration, as well as the new 2012-2017 program that will be crafted by the current administration.

If there is enough interest from industry and if the government determines that offshore drilling does not harm the environment or interfere with military activities, the Interior Department intends to hold a 2012 lease sale for exploration 50 miles off the coast of Virginia, as well as a similar one for Alaska’s Cook Inlet.

The Interior Department estimates that the Gulf of Mexico contains 36 billion to 41.5 billion barrels of undiscovered, economically recoverable oil and 161 trillion to 207 trillion cubic feet of undiscovered, recoverable natural gas resources.

Offshore oil drilling has been prohibited since the 1980s, both under congressional and presidential moratoriums. Bush lifted the presidential ban in 2008, and Congress declined to impose its ban yet again through the annual spending process.