FILE PHOTO: An oil and gas drilling platform stands offshore near Dauphin Island, Alabama, October 5, 2013. REUTERS/Steve Nesius/File Photo

(Reuters) - U.S. Senate Democrats are questioning the legal basis of the Trump administration’s move to continue work on its five-year offshore drilling plan during the partial federal government shutdown.

In a letter sent on Tuesday to David Bernhardt, the Department of Interior’s acting secretary, and Walter Cruickshank, acting director of the Bureau of Ocean Energy Management (BOEM), the senators asked them to address why the BOEM’s contingency plan was updated in January to allow 40 employees to work on the offshore leasing program.

It specifically asked on what legal basis the department changed its treatment of offshore oil and gas activities between Dec. 22, when the shutdown began, and January, when it recalled the employees. The letter requested a response by Feb. 1.

“While the oil industry might view a delay in the approval of new offshore drilling as an emergency, the American people deserve regulators who prioritize safety and environmental protection over political expediency and the wishes of moneyed special interests,” said the letter, which was signed by 14 legislators.

Signing the letter were Democratic Senators Robert Menendez, Cory Booker, Edward Markey, Richard Blumenthal, Jack Reed, Ron Wyden, Jeff Merkley, Sherrod Brown, Patrick Leahy, Ben Cardin, Dianne Feinstein, Jeanne Shaheen and Tom Carper and an independent, Bernie Sanders.

The longest U.S. government shutdown in history reached its 33rd day on Wednesday. The Department of Interior, which oversees energy development on federal lands and waters, is among the departments included in the shutdown. The BOEM falls under the Interior Department.

“As the letter clearly states, Senator Menendez and his colleagues are opposed to any offshore oil and gas development in the United States, regardless of whether or not we are experiencing a partial government shutdown,” Interior Department spokeswoman Faith Vander Voort said in an email. “We will be responsive to their letter in a timely manner.”

In addition to tapping employees to work on the offshore drilling program, the BOEM temporarily recalled some furloughed workers to prepare an upcoming Gulf of Mexico oil lease sale using funds left over from last year, according to a department document.

House of Representatives Democrats from the Natural Resources Committee will host a forum of environmentalists and former policymakers on the topic on Thursday, they said in a press release.