The political environment in Washington has changed drastically since Donald Trump entered the White House, and some of that has played out at the luxury hotel he opened down the street during his presidential campaign.

The Trump International Hotel in the Old Post Office building on Pennsylvania Avenue has effectively become a secondary White House, where Republican figures gather and those looking to influence the administration can mingle with Cabinet members, the Washington Post reports.

The Post, which spent part of every day for a month inside the hotel, identified key Republican figures — within and outside of the administration — dining, booking rooms or attending events in the hotel, and reporters documented hundreds of thousands of dollars being spent by interest groups and foreign governments.

The Trump Organization leased the Old Post Office Building from the General Services Administration in 2013 to redevelop it into a 263-room luxury hotel, which opened in September and had brought in $19.7M in revenue as of April, according to Trump's latest financial disclosure. Trump in January decided to hand over management of the company to his sons but to retain his ownership stake, which has created ethical and legal concerns around the hotel.

While political activity has traditionally taken place in hotels and restaurants throughout the city, having a building five blocks from the White House that bears the president's name, an unprecedented phenomenon, has created a hub for Republican politics. Influential conservative figures who have hosted events, taken meetings or spent time or money at the hotel, according to the Post, include Secretary of the Treasury Steve Mnuchin, former Press Secretary Sean Spicer, former New York City Mayor Rudy Giuliani, former Trump campaign manager Corey Lewandowski, Sen. Rand Paul (R-Ky.), Reps. Dana Rohrabacher (R-Calif.) and Bill Shuster (R-Pa.), Maine Gov. Paul LePage and Milwaukee Sheriff David Clarke.

It has also attracted foreign governments looking to influence U.S. policy. The Kingdom of Saudi Arabia paid roughly $270K at the hotel on behalf of veterans groups that were there to lobby Congress against a law allowing 9/11 victims to sue Saudi Arabia.