Lead1 joins a growing list of corporate entities, advocacy groups and embassies conducting business at Trump International Hotel in Washington. (Bill O’Leary/The Washington Post)

When former Maryland congressman Tom McMillen took the helm of an advocacy group looking to gain influence in Washington, he decided the group’s first “Congressional Gala” ought to take place in the new haunt of an old acquaintance: Donald Trump.

McMillen’s group, an association of college athletic directors looking to quash proposals that would allow scholarship athletes to be paid, booked the chandelier-adorned Presidential Ballroom in Trump’s D.C. hotel for a 600- to 700-person gala in September of this year.

The event will combine the tried-and-true Washington practice of seeking to influence elected officials with the fresh twist of paying a company owned by the president of the United States. Bookings at Trump’s hotel create potential ethical conundrums going forward as groups seeking political influence in Washington decide where to take their conference business, experts say.

The president-elect is expected to address questions about his business dealings at a news conference scheduled for 11 a.m. Wednesday.

McMillen’s organization, known as Lead1, plans to form a political action committee to fund candidates for the House and Senate. According to an early draft of the brochure for the event, “the LEAD1 College Sports Congressional Gala will be a one of a kind event” that will allow athletic directors to meet with “members of Congress, and special guests, including the President and Vice President of the United States.” A later draft omitted the direct reference to the president and vice president and referred only to “administration officials.”

The drafts were produced by a consultant without the group’s knowledge, McMillen said. He added that the draft has not yet been finalized.

McMillen, a former House Democrat from Maryland, said he has known Trump at least since 1985, when the real estate magnate was an early donor to his first campaign.

Even though the group’s guests will be staying and holding meetings at a competing hotel nearby, the Mandarin Oriental, McMillen said he decided to hold the gala at the Trump International Hotel because he was seeking a larger ballroom for the event. The Trump hotel has a 13,200-square-foot ballroom, the largest luxury meeting space in the city, while the Mandarin advertises an 8,300-square-foot grand ballroom that can seat up to 770 guests for a banquet.

McMillen also said his previous connection with Trump influenced his decision.

“It’s a great venue,” McMillen said. “It’s large, it’s got capacity and obviously I’ve had relations with the president-elect for 30 years.”

In booking the Trump hotel, McMillen’s group, Lead1, joins a growing list of corporate entities, advocacy groups and embassies conducting business at the 263-room hotel, which opened officially in October in the Old Post Office Pavilion on Pennsylvania Avenue NW.

In November, several foreign diplomats, including some from the Middle East and Asia, told The Washington Post that they had opted to stay and to spend money at Trump’s hotel because it was a friendly gesture to the incoming president.

The Kuwaiti Embassy booked the hotel’s ballroom for its Feb. 25 National Day celebration after initially considering the Four Seasons. Bahrain held its National Day event at the hotel, and Jewish leaders joined the Embassy of Azerbaijan in hosting a Hanukkah Party at the hotel. The National Confectioners Association and the Young America’s Foundation have also held events there.

McMillen said he saw nothing wrong with booking Trump’s ­hotel at a time when his group is seeking to build political relationships, comparing Trump’s wealth to that of previous presidents John F. Kennedy and George Washington.

“I’m sure Washington had conflicts, too. He owned tons of land in the western frontier, so he had tons of conflicts,” he said. “It was an interesting time. Real estate is a tough thing because you can’t sell it, and I think back to presidents that had great wealth.”

Critics, however, see difficult ethical issues and possible conflicts of interest raised by Trump’s ownership of the hotel.

Richard Painter, who served as the chief White House ethics lawyer for President George W. Bush from 2005 to 2007, said that Lead1’s plans are concerning because they place a group seeking political influence into a personal business transaction with the Trump Organization.

“Any intermingling with U.S. government business and Trump Organization business is very risky,” Painter said. “I would, at a bare minimum, with respect to this particular event, prohibit White House personnel from attending.”

Norm Eisen, who acted as the chief White House ethics lawyer for President Obama from 2009 to 2011, said Trump’s “only way” out of ethical dilemmas is to make a clean break from his businesses and to appoint an independent trustee.

“If he did that, then there would be no question of whether people can influence him by attempting to do business with him,” Eisen said.

A spokeswoman for the Trump Organization declined to comment. The president-elect has said that he will put his sons Eric and Donald Trump Jr. in charge of the businesses when he enters office and that no new deals will be pursued.

Lead1, founded in 1986, was previously called the D1A Athletic Directors’ Association and based in Dallas. Its members are the 129 athletic directors of the schools in the NCAA’s Football Bowl Subdivision (FBS), formerly known as Division I-A, the top tier of collegiate football programs that are eligible to compete for the national championship, which Clemson University won Monday night with a 35-31 triumph over the University of Alabama.

In recent years, as the prospect of pay for college athletes gained steam, the group hired McMillen, relocated to the Washington area, renamed itself Lead1 and declared it would create a political action committee (for which the paperwork has not yet been filed). The PAC will be funded by individual contributions from the athletic directors.

Dan Radakovich, Clemson’s athletic director, said that most athletic directors know a number of congressman in their individual states. He said it made sense to move Lead1’s annual meeting to Washington, where the group could bring together members of Congress for a high-profile event.

“We don’t know where college athletics is going to go in a few years,” he said Saturday in a phone interview from Tampa. “As athletic directors, we want to have a voice if there are any changes. It would be a great time to have some type of a presence in the Washington, D.C., community . . . inside the Beltway, so to speak.”

McMillen, a former University of Maryland basketball star who went on to play professionally for the New York Knicks and Washington Bullets, among other teams, said he has known Trump since his playing days and was briefly rumored (he says inaccurately) in 1990 to have dated Marla Maples, who became Trump’s second wife.

McMillen said he began identifying members of Congress in positions to protect college programs from the “devastating” effects of paying amateur athletes, who he said already benefit tremendously from athletic scholarships.

He offered the example of a women’s basketball player who could be riding the bench but receiving more than $100,000 in annual tax-free benefits.

“Not only does she get the scholarship but she gets room and board, she gets unlimited meals, she gets health care, she gets emergency travel if she needs it for her family, she gets unlimited tutoring,” he said. “So there are unlimited benefits for this kid.”

Andrew Zimbalist, an expert on the business of college sports, said as the issue heats up the new Lead1 PAC will be seeking to exert its influence on Capitol Hill and the Trump administration.

“Their end game is that they want to maintain the system as close to its current form as possible,” said Zimbalist, an economics professor at Smith College. “They want to maintain NCAA amateurism. It’s under fire.”

A variety of litigation has been brought in recent years against universities and the NCAA concerning the treatment of athletes, focusing on whether they can be paid or receive publicity rights. Last month, the U.S. Court of Appeals for the 7th Circuit affirmed a lower district court’s ruling that two track and field athletes at the University of Pennsylvania were not employees and thus not eligible for payment. The athletes sued the NCAA to seek minimum-wage payments, claiming they should be entitled to compensation under the Fair Labor Standards Act.

But Zimbalist said similar cases are likely to keep “popping up” around the country. He said it makes “perfect sense” for McMillen to mobilize his association of athletic directors for political action.

“If they’re not paying athletes, they can spend more money on salaries for coaches and for themselves,” Zimbalist said. “Everything has been going in the right direction for them.”