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President Obama, reversing a long-standing ban on most offshore drilling, unveiled a plan Wednesday to allow oil drilling off the Eastern seaboard and potentially the western coast of Florida.

While the plan is sure to rile environmentalists, the announcement comes just a day before the administration will please them -- and anger conservatives -- by cementing sweeping emissions and fuel economy standards that will impact U.S. auto manufacturers.

The Environmental Protection Agency and Department of Transportation on Thursday are expected to sign the final rule establishing emissions and fuel economy standards for the U.S. auto fleet. Those standards call for new vehicles to average 35.5 miles per gallon by 2016. It will cover model years 2012 through 2016, and is estimated to cost up to $1,300 per  vehicle.

House Minority Leader John Boehner called such regulations part of a "new massive job-killer" in a statement Wednesday.

Obama, speaking at Andrews Air Force Base in Maryland, defended the changes, saying the move will reduce dependence on oil and ultimately save money by helping drivers spend less on gas.

But the administration may have been trying to balance the controversial auto rule against the Republican-favored call to open up some U.S. waters to drilling. Hinted at for months, the plan modifies a ban that for more than 20 years has limited drilling along coastal areas other than the Gulf of Mexico.

The president, stressing he did not come to the drilling decision "lightly," said Wednesday that domestic oil production will not solve the country's energy problems but that "homegrown fuels" are needed to move away from foreign oil and help "transition" to more clean-energy sources.

"The bottom line is this -- given our energy needs, in order to sustain economic growth, and produce jobs, and keep our businesses competitive, we are going to need to harness traditional sources of fuel even as we ramp up production of new sources of renewable, homegrown energy," Obama said.

White House officials pitched the changes as ways to reduce U.S. reliance on foreign oil and create jobs, but the president's decisions also could help secure support for a climate change bill that is languishing in Congress -- though Republicans' initial reaction to the announcement Wednesday was negative.

The plan would open up drilling 50 miles off Virginia's coast. In addition, the Interior Department has prepared a plan to add drilling platforms in the eastern Gulf of Mexico, 125 miles off the coast of Florida, if Congress allows a moratorium to expire. Drilling already takes place in western and central areas of the Gulf of Mexico.

Obama, joined by Interior Secretary Ken Salazar, also announced that proposed leases in Alaska's Bristol Bay will be canceled. The Interior Department also planned to reverse last year's decision to open up parts of the Chukchi and Beaufort seas. Instead, scientists will study the sites to see if they're suitable for future leases.

Obama is allowing an expansion in Alaska's Cook Inlet to go forward, but the plan leaves in place a moratorium on drilling off the West Coast.

Boehner called the new drilling opportunities off the Virginia coast "positive," but he questioned why the administration wouldn't expand exploration far beyond that. He said the plan falls short.

"The Obama administration continues to defy the will of the American people who strongly supported the bipartisan decision of Congress in 2008 to lift the moratorium on offshore drilling not just off the East Coast and in the Gulf of Mexico, but off the Pacific Coast and Alaskan shores as well," Boehner said in a written statement. "Keeping the Pacific Coast and Alaska, as well as the most promising resources off the Gulf of Mexico, under lock and key makes no sense at a time when gasoline prices are rising and Americans are asking 'Where are the jobs?'"

Rep. Mike Pence, R-Ind., called the plan a "smokescreen" that would delay new exploration until at least 2012 and include a "fraction" of the resources in the Bush administration's plan.

"Unfortunately, this is yet another feeble attempt to gain votes for the president's national energy tax bill that is languishing in the Senate," he said.

Bush opened the door to Obama's change in policy when he lifted a drilling ban in 2008, at the same time lawmakers allowed a similar moratorium to expire.

The president's team has been busy on energy policy and Obama talked about it in his State of the Union address in January.

Obama also has urged Congress to complete work on a climate change and energy bill, which has remained elusive. The president met with lawmakers earlier this month at the White House about a bill cutting emissions of pollution-causing greenhouse gases by 17 percent by 2020. The legislation would also expand domestic oil and gas drilling offshore and provide federal assistance for constructing nuclear power plants and carbon sequestration and storage projects at coal-fired utilities.

White House officials hope Wednesday's announcement will attract support from Republicans, who adopted a chant of "Drill, baby, drill" during 2008's presidential campaign.

The Associated Press contributed to this report.