With Washington poised to pull the Atlantic Ocean off the oil and gas drilling list, environmentalists declared victory after their hard preservation efforts.

The White House is expected to announce plans to remove portions of the Atlantic from consideration in a drilling lease plan. Washington in 2014 opened up Atlantic waters from Virginia to Florida for seismic testing, though advocacy group Oceana said there are more than 100 members of Congress and regional municipalities that have stated their public opposition to oil and gas activity in the Atlantic.

Sierra Weaver, an attorney with the Southern Environmental Law Center, said staying with the original plans for the region would've moved in stark contrast to the chorus of voices expressing concern.

"This is an incredible day," she said in an emailed statement. "It would reflect the hard work of thousands of people and a collection of communities and elected leaders from both parties who stood up to protect the Southeast's beautiful beaches."

In February, Virginia Lt. Gov. Ralph Northam added his name to a growing list of opponents to Atlantic drilling plans, saying the regional tourism industry would be threatened by oil and gas development.

This week, the U.S. Defense Department said it was concerned drilling would interfere with military maneuvers. Pentagon spokesman Matthew Allen told The Washington Post the military has outlined areas where defense operations, such as missile tests and other readiness maneuvers, "are not compatible, partially compatible or minimally impacted by oil and gas activities."

Supporters said opening new areas to explorers would provide stimulus to regional economies. Mike Ward, the executive director of the Virginia Petroleum Council, has said the industry already supports about 140,000 jobs in the Virginia and adds more than $7 billion to state coffers.

Erik Milito, director of industry operations for the American Petroleum Institute, said opening the Atlantic up to drillers is a once-in-a-generation opportunity.

Apart from the potential for spills, advocacy groups said the noise from seismic surveys used to get a better understanding of the reserve potential threatens marine ecosystems.

"Our nation has seen the devastation that comes from offshore drilling, and the benefits are simply not worth the risks," Oceana Vice President Jacqueline Savitz said in an emailed statement.