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Housekeepers and guest-room workers at the Trump International Hotel Washington have voted to join a labor union, The Washington Post reports, adding one more potential conflict of interest to the already long list of controversies swirling around the hotel.

About 40 employees—95 percent of the hotel’s housekeeping staff—voted last week to join Unite Here Local 25 and another 80 members of the waitstaff are likely to vote on union membership in the months ahead, according to the Post.

When workers at Trump’s Las Vegas hotel voted to join the Nevada chapter of Unite Here, it triggered a lengthy and high-profile battle. While deals were eventually settled in the weeks before the inauguration, the real estate magnate now has the power to appoint members of the National Labor Relations Board, which rules over such disputes.

Trump originally claimed he would divest from his businesses, but later decided to simply “resign” while retaining his ownership stake. His D.C. hotel has become one of the most high-profile examples of the web of conflicts of interest that arise from that decision.

For one, House Democrats argue that by retaining a stake in the hotel, the president is in violation of the 60-year lease with the GSA, signed in 2012, that states that no elected official of the U.S. government could have a part in the lease or any benefit that comes from it.

A government ethics watchdog, meanwhile, filed a federal lawsuit against the president last week, claiming his global business interests mean that he is personally making money off foreign governments—a violation of the Emoluments Clause. Trump’s attorneys argue that the clause doesn’t apply to fair-market transactions, according to the Post.