The White House is taking steps that could open up new areas of the Atlantic and Arctic oceans to offshore oil and gas drilling, according to multiple individuals briefed on the proposal.

The White House is considering an executive order instructing the Interior Department to reverse President Barack Obama’s withdrawal of hundreds of millions of offshore acres from future drilling in December.

The executive order — which could come out in the next few weeks — represents President Trump’s latest attempt to promote domestic energy exploration by rolling back restrictions put in place by previous administrations, though it would take considerable time for Interior to carry out aspects of the proposed directive.

Interior Secretary Ryan Zinke on Thursday, in an address to the annual meeting of the National Ocean Industries Association, confirmed that there was an executive order addressing offshore, “on the way … likely next week,” according to Nicolette Nye, a spokeswoman for the group.

However, Interior spokeswoman Heather Swift said that Zinke was alluding to the executive order Trump signed last week and that the department was “reviewing our offshore policies and regulations.”

Other oil industry officials, participants at the NOIA meeting, and a GOP lawmaker from an affected state said that they had not been briefed and that the order might not be issued any earlier than May. People familiar with the planned order spoke on the condition of anonymity because it has not been formally announced yet.

Zinke’s comments highlighted the extent to which Trump’s March 28 executive order is already reverberating throughout the federal government. That directive instructed the heads of all agencies to “review all existing regulations, orders, guidance documents, policies, and any other similar agency actions (collectively, agency actions) that potentially burden the development or use of domestically produced energy resources, with particular attention to oil, natural gas, coal, and nuclear energy resources.”

Andrew Weissman, senior counsel at Pillsbury Winthrop Shaw Pittman, said in an interview that industry officials, legal experts and others are just beginning to understand how the order could affect “almost every environmental regulation that affects energy in any way” as well as many non-environmental rules.

“It literally applies to everything the federal government does that affects energy development and use,” he said.

How Trump is rolling back Obama’s legacy

The Pacific coast has been closed to new oil and gas exploration since the disastrous oil spill off Santa Barbara, Calif., in 1969. There has been no drilling off the Atlantic coast since the early 1980s.

Early in his administration, Obama considered allowing seismic work in preparation for exploration off the southeastern coast, from Florida to Virginia.  And he did not move to stop Royal Dutch Shell from drilling an exploratory well in the Chukchi Sea off Alaska’s Arctic coast; the well turned out to be a dry hole. But near the end of his presidency he closed off vast areas.

The Trump directive under consideration has two elements, according to people familiar with it. One part would instruct Interior to revise its current five-year leasing plan to schedule sales of some areas in both the Arctic and Atlantic Ocean, which are not included now. A second part would rescind the designation Obama made under the Outer Continental Shelf Lands Act (OCSLA) in December to withdraw large portions of the Chukchi and Beaufort seas in the Arctic and a string of undersea canyons in the Atlantic stretching from Massachusetts to Virginia from leasing for an indefinite period.

Bloomberg first reported news of the directive on Thursday.

Environmental groups are sure to challenge both initiatives in court, and the effort to rescind the protections Obama put in place under OSCLA could prove difficult to defend because a president has not reversed such a move in the past. But presidents have wide latitude to revise the Interior Department’s five-year leasing plan, and have done so in the past, so it is unclear how any challenge to that element of the order would fare in court.

Jacqueline Savitz, Oceana’s senior vice president for the United States, said in an email that the administration would soon find there is widespread opposition to renewed drilling efforts.

“Expanding offshore drilling into new areas like the Arctic, Atlantic and Pacific oceans would put vibrant ocean ecosystems at risk and be bad for business, threatening thriving coastal economies and lucrative industries, including tourism, recreation and fishing,” Savitz said.

“Business leaders along the Atlantic coast have been vocal in their opposition to offshore drilling, and the decades-long push to drill in the Arctic has put its unique and diverse ecosystem at risk, cost tens of billions of dollars and created significant controversy without profitable results.”

It remains unclear whether opening up the remote Chukchi and Beaufort Seas for leasing would attract any bids. After Shell spent more than $7 billion to lease and drill an uneconomic well, other major oil companies have dropped plans to drill in the region.

Brady Dennis contributed to this article.