The Obama administration’s plan adopts some drilling proposals floated by President George W. Bush near the end of his tenure, including opening much of the Atlantic and Arctic Coasts. Those proposals were challenged in court on environmental grounds and set aside by President Obama shortly after he took office.

Unlike the Bush plan, however, Mr. Obama’s proposal would put Bristol Bay, home to major Alaskan commercial fisheries and populations of endangered whales, off limits to oil rigs.

Actual drilling in much of the newly opened areas, if it takes place, would not begin for years.

Mr. Obama said several times during his presidential campaign that he supported expanded offshore drilling. He noted in his State of the Union address in January that weaning the country from imported oil would require “tough decisions about opening new offshore areas for oil and gas development.”

Perhaps in anticipation of controversy, the new policy has been closely held within the administration. White House and Interior Department officials began briefing members of Congress and local officials in affected states late Tuesday.

It is not known how much potential fuel lies in the areas opened to exploration, although according to Interior Department estimates there could be as much as a three-year supply of recoverable oil and more than two years’ worth of natural gas, at current rates of consumption. But those estimates are based on seismic data that is, in some cases, more than 30 years old.

The first lease sale off the coast of Virginia could occur as early as next year in a triangular tract 50 miles off the coast that had already been approved for development but was held up by a court challenge and additional Interior Department review, officials said.

But as a result of the Obama decision, the Interior Department will spend several years conducting geologic and environmental studies along the rest of the southern and central Atlantic Seaboard. If a tract is deemed suitable for development, it is listed for sale in a competitive bidding system. The next lease sales — if any are authorized by the Interior Department — would not be held before 2012.