Experts say foreign leaders’ stays at Donald Trump’s Washington hotel could violate the Constitution when he enters office Jan. 20. (AP)

Donald Trump’s company is pitching foreign diplomats on his D.C. hotel as a place to book rooms and hold meetings, the kind of marketing that would hardly raise eyebrows at any other luxury accommodation in the nation’s capital. But when the owner is about to become president, such entreaties eventually could run afoul of a clause in the U.S. Constitution that bars the president from accepting gifts from foreign leaders.

Article 1, Section 9 of the Constitution includes an “emoluments clause.” The dictionary defines ’emolument’ as a salary, fee or profit from one’s office or employment. The rule bars any person holding an office of the United States from accepting “any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State” without approval from Congress.

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Constitutional and government ethics experts say Trump’s hotel business raises myriad questions about where to draw the line, and the emoluments clause could become an issue the day he enters office.

Richard Painter, a University of Minnesota law professor who served as chief ethics counsel for President George W. Bush, said in an interview with the web site ThinkProgress that business from official dignitaries “looks like a gift” and “had better stop by January 20.”

Laurence Tribe, a constitutional law professor at Harvard with extensive experience arguing before the Supreme Court, agreed with that assessment on Twitter Saturday.

Even right-wing outlet the Daily Caller said Monday that the arrangement could “trigger a constitutional crisis.”

Trump has yet to address such concerns publicly. Since the election, he recently included his daughter Ivanka Trump (one of the people he said would run his businesses while he is president) in a meeting with the prime minister of Japan, and he has met with Indian business partners.

“We will have our White House counsel review all of these things” incoming White House chief of staff Reince Priebus told CNN. Priebus did not offer specifics but said Mr. Trump’s conduct as president will be “certainly compliant with the law.”

Unlike many of his namesake businesses, Trump has a lot at stake in the performance of his D.C. hotel. With other properties, Trump sometimes contracts out the use of his name to people who actually own the buildings; in Washington, he is the majority owner and has millions of dollars riding on the project’s success.

According to the financial disclosure form he filed with the Federal Elections Commission as a candidate, Trump owns 76.725 percent of the D.C. hotel project. Three of his children, Don Jr., Ivanka and Eric, each have 7.425 percent of the project, according to documents dug up by Buzzfeed. The hotel is in a historic building, the Old Post Office Pavilion, that is still owned by the federal government and overseen by the General Services Administration.

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If the project goes bad, Trump’s company could be on the hook for a $170 million loan from Deutsche Bank.

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.

The official who oversaw the selection of Trump for the project, Robert A. Peck, formerly of the GSA, said in an interview that Trump’s lack of action to address the conflict of interest issue was “pretty breathtaking.”

Peck said he couldn’t imagine the average federal employee feeling much empowered to negotiate with one of Trump’s children while they also advised their father in the White House, if he holds on to the property.

“It would be one thing if his kids ran the business, if his kids didn’t also want to be White House advisers. But even then, the specter of some … contracting officers sitting across the table from Eric Trump. How does that feel?” he said.

It’s increasingly clear that sorting through Trump’s business activities while he is president will fall to Congress. And few members of Congress knows the D.C. hotel project better than D.C. Del. Eleanor Holmes Norton (D), who pushed relentlessly for the building to be reused when it was occupied by a food court and a smattering of government offices.

Norton issued a statement saying that Trump’s businesses put the country in uncharted legal territory and that she didn’t expect any quick resolution.

“President-elect Trump’s business holding in the Old Post Office building, and other properties around the world, is a sui generis case — something new for a president-elect,” Norton said. “It will take lawyers for Mr. Trump and the government some time to figure out what must be done with regard to his business holdings.”

Follow Jonathan O’Connell on Twitter: @oconnellpostbiz