Rep. Elijah Cummings (D-MD.) and other House leaders say Donald Trump could violate his hotel lease with the government the day he takes office. (Melina Mara/TWP)

Four Democrats in the House of Representatives and two in the Senate are pushing a federal agency to address potential conflicts of interest and contractual violations that could arise when Donald Trump becomes president in January.

Trump’s firm leases the Old Post Office Pavilion, which is federally owned, from the General Services Administration on a 60-year deal.

However despite Trump’s recent vow to separate himself from his businesses once he takes office, he may still run afoul of a clause in the lease barring any “elected official of the Government of the United States” from deriving “any benefit” from the agreement.

The issues prompted Democratic Reps. Elijah E. Cummings (Md.), Peter A. DeFazio (Ore.), Gerald E. Connolly (Va.) and André Carson (Ind.) to write GSA Administrator Denise Turner Roth Wednesday asking how she planned to address what they called “the imminent breach-of-lease and conflict of interest issues” in the deal.

“We do not see this as an ambiguous provision, but as a strict and categorical ban,” they wrote, referring to the clause. “The contractual breach threatened by Mr. Trump’s swearing-in is compounded by the general and egregious conflict of interest poised by his appointing the GSA Administrator who will oversee this lease with his hotel.”

“This is not a hypothetical conflict —  there is a clear and very real conflict that will be triggered the moment Mr. Trump is sworn in as President of the United States unless concrete steps are taken now to avert it.”

The representatives asked the GSA for a briefing on the matter by Dec. 7.

On Thursday Sens. Elizabeth Warren (Mass.) and Tom Carper (Del.) wrote Roth with similar concerns, saying that the GSA “should immediately take steps to identify and mitigate any potential conflicts of interest relating to its lease agreement” with Trump.

The senators also raised concerns that the hotel’s business with foreign leaders could violate the Constitution’s Emoluments Clause once Trump takes office. Their letter was reported earlier by MSNBC.

GSA officials have yet to respond to the letters but they have repeatedly issued a statement in response to previous questions on the lease saying the agency “plans to coordinate with the President-elect’s team to address any issues that may be related to the Old Post Office building.”

GSA Inspector General Carol F. Ochoa could also be in a position to act. A spokeswoman in her office declined to comment.

GSA officials have also said they rely on the Office of Government Ethics for guidance on how to address such potential conflicts. A spokesman there repeatedly declined to speak about the Trump hotel on the record. The office’s Twitter account, though, issued a series of tweets that were posted, removed and posted again, applauding Trump’s tweet that he would separate himself from his businesses and stating that the “only way to resolve these conflicts of interest is to divest.”

[Trump’s pledge to leave his business prompts calls to divest.]

Writing in The Washington Post a week after the election, procurement experts Steven L. Schooner and Daniel I. Gordon argued that Trump would violate the lease the day he entered office because of that clause.

Other experts say that while there are obvious conflicts of interest in allowing Trump to have a stake in the hotel while serving as president, he may not technically be in violation of the lease.

The phrasing of the clause is long-standing boilerplate that may not have a clear legal interpretation, said Georgetown University law professor Gregory Klass.

“Parts of it date back at least to the Civil War,” he said. “It could be read to prohibit an elected official from keeping a beneficial interest after elected — that is, to cover the Trump case. And the term’s clear purpose is to prevent conflicts of interest of that type. But the language is not crystalline.”

Klass said the obvious solution would be for Trump to “simply divest his family from this and any other contracts he has with the U.S. Government.”

There is a provision in the federal lease allowing Trump to sell or transfer his stake in the hotel to “any Trump Family Member.” Selling it to an outside entity would likely require approval by the GSA.

Some of the Obama administration’s options may be limited because that clause would not go into effect until Trump is sworn in, leaving the issue to his own administration.

Related: The Constitution may have something to say about how Trump runs his D.C. hotel

This story has been updated.

Follow Jonathan O’Connell on Twitter: @oconnellpostbiz