Since the election, it has been clear that Donald Trump cannot both be president and maintain a lease on the government-owned Old Post Office building in Washington, where he opened an opulent hotel last year. Now, a federal official who works for the agency that negotiated the lease (and that, conveniently, reports to the president) has come up with a bizarre, tortured and ultimately dishonest rationale for why Mr. Trump can keep it.

Mr. Trump’s 2013 lease with the General Services Administration stipulates that no elected official “shall be admitted to any share or part of this Lease, or to any benefit that may arise therefrom.” Legal experts say the president is clearly in violation of that clause and the government should either terminate the lease or force Mr. Trump to transfer it to somebody else. On Thursday, however, an agency contracting official, Kevin Terry, declared that the president was not in violation because he had agreed not to receive any profits from the hotel until after he leaves office.

Mr. Terry engages in legal gymnastics that no lawyer could credibly defend. It should not matter when Mr. Trump accepts the profits from the hotel; he benefits even if he waits until after he leaves the White House to pocket them. Mr. Terry argues that as long as Mr. Trump’s profits are reinvested in the hotel, rather than deposited in his bank account, there is no violation. But by reinvesting the profits, Mr. Trump is increasing the value of the hotel and its ability to earn more money in the future. He has a 60-year lease on the building, and not pocketing profits for a few years is hardly a sacrifice.

Then there’s the not-so-little matter of the Constitution, which Mr. Trump is violating by owning the hotel. Article I of the Constitution prohibits all federal government officials from accepting gifts, profits and other payments from foreign governments without the approval of Congress. As it happens, foreign governments have been booking rooms and hosting events at the Trump hotel. In addition, Article II of the Constitution specifically bars the president from earning any emoluments, or profits, from the federal government or state governments in addition to his salary. Experts say that clause prohibits Mr. Trump’s Washington hotel and his other businesses from earning money or receiving other benefits from federal or state agencies — including Mr. Terry’s decision to let Mr. Trump keep the lease.