The proposal — a compromise that will please oil companies and domestic drilling advocates but anger some residents of affected states and many environmental organizations — would end a longstanding moratorium on oil exploration along the East Coast from the northern tip of Delaware to the central coast of Florida, covering 167 million acres of ocean…

The environmentally sensitive Bristol Bay in southwestern Alaska would be designated as a sanctuary and no drilling would be allowed under the plan, officials said. But large tracts in the Chukchi Sea and Beaufort Sea in the Arctic Ocean north of Alaska — nearly 130 million acres — would be eligible for exploration and drilling after extensive studies…

The proposal is intended to reduce dependence on oil imports, generate revenue from the sale of offshore leases and help win political support for comprehensive energy and climate legislation.

But while Mr. Obama has staked out middle ground on other environmental matters — supporting nuclear power, for example — the sheer breadth of the offshore drilling decision will take some of his supporters aback. And it is no sure thing that it will win support for a climate bill from undecided senators close to the oil industry, like Lisa Murkowski, Republican of Alaska, or Mary L. Landrieu, Democrat of Louisiana.