Friday evening, the Washington Post reported that about 100 foreign diplomats gathered at President-elect Donald Trump’s hotel in Washington, DC to “to sip Trump-branded champagne, dine on sliders and hear a sales pitch about the U.S. president-elect’s newest hotel.” The tour included a look at the hotel’s $20,000 a night “town house” suite. The Post also quoted some of the diplomats saying they intended to stay at the hotel in order to ingratiate themselves to the incoming president.

“Why wouldn’t I stay at his hotel blocks from the White House, so I can tell the new president, ‘I love your new hotel!’” said one diplomat from an Asian nation. “Isn’t it rude to come to his city and say, ‘I am staying at your competitor?’”

The incoming president, in other words, is actively soliciting business from agents of foreign governments. Many of these agents, in turn, said that they will accept the president-elect’s offer to do business because they want to win favor with the new leader of the United States.

In an exclusive exchange with ThinkProgress, Richard Painter, a University of Minnesota law professor who previously served as chief ethics counsel to President George W. Bush, says that Trump’s efforts to do business with these diplomats is at odds with a provision of the Constitution intended to prevent foreign states from effectively buying influence with federal officials.

The Constitution’s “Emoluments Clause,” provides that “no person holding any office of profit or trust under” the United States “shall, without the consent of the Congress, accept of any present, emolument, office, or title, of any kind whatever, from any king, prince, or foreign state.”

The diplomats’ efforts in seek Trump’s favor by staying in his hotel “looks like a gift,” Painter told ThinkProgress in an email, and thus is the very kind of favor the Constitution seeks to prevent.

To explain, the ordinary rule under the Emoluments Clause is that federal officials may do business with foreign governments so long as they do not receive special treatment. If the president owns a $200,000 Rolls Royce, Painter told ThinkProgress, they can sell that car to the Queen of England, so long as they only receive its fair market value. If Her Majesty The Queen pays $250,000 for the Rolls Royce, however, that would violate the Emoluments Clause.

There’s a catch, however, for someone like Trump who trades on the value of his own name. “Anything in excess of fair market value is a gift,” according to Painter, “and I don’t think you can take into account the value of the name Trump in calculating fair market value.” The diplomats are not staying in one of Trump’s expensive luxury hotels because Trump is charging their nation a reasonable market rate for a night’s stay. They are staying in the hotel because of the added value that comes from doing business with the President of the United States.

“It had better stop by January 20,” says Painter.

In a follow up exchange, ThinkProgress asked whether Trump really can cure this impending violation of the Emoluments Clause by acting differently once he is sworn in as president. After all, the message that diplomats can earn the favor of the new president by staying in his hotels has already been received, and it can’t exactly be unsaid.

Painter responded that “the only good answer,” for the president-elect “is to sell the hotel or give it to his kids (and pay the gift tax) by January 20.”

Assuming that Trump does not divest from his hotel, however, it may prove difficult to enforce the Constitution against him. There are few court cases dealing with the Emoluments Clause. Typically, the country has relied on internal safeguards within the executive branch and fear of political embarrassment to prevent violations by the president.

Moreover, while it is conceivable that a rival hotel may have standing to sue Trump for taking away its business with foreign diplomats in violation of the Constitution, it’s far from clear that any hotel business will want to risk a feud with the notoriously vindictive president-elect.

There is, however, at least one remedy under the Constitution for such a violation of the public trust by the president: impeachment.

Originally published by ThinkProgress