Washington CNN  — 

The House Transportation and Infrastructure Committee issued a subpoena to the General Services Administration on Thursday for documents concerning the Trump International Hotel’s lease of its building in downtown Washington, DC.

GSA – the agency which supervises the lease of the Old Post Office building to the Trump Organization – has refused to fully comply with the committee’s document requests, according to the committee.

“Political appointees at the GSA are trying to hide behind a pathetic excuse that Congress – a co-equal branch of the Federal government tasked with conducting oversight – can’t have key documents regarding a federally-owned property currently leased by the President,” Committee Chairman Peter DeFazio, D-Oregon, said in a statement.

“The American people have a right to know whether the President of the United States, who is serving as both the landlord and tenant of the Old Post Office Building, is violating the Emoluments Clauses of the US Constitution to enrich himself,” he added.

The committee is investigating President Donald Trump’s potential conflicts of interest and violation of the Constitution’s emolument clause due to his real estate ties. Although Trump resigned from his companies before taking office, he transferred his assets into a trust that he can dissolve anytime he chooses. This arrangement allows him to benefit financially from those businesses, including the DC hotel.

The subpoena on Thursday covers all documents that the committee previously asked for in January 22, including legal and financial records that GSA has repeatedly refused to provide, according to the committee.

In January, a watchdog report found that GSA improperly “ignored the Constitution” when deciding to maintain the lease of the Old Post Office Building to the Trump International Hotel after he was elected to the White House.

CNN reported last year that an employee for the federal agency supervising the lease for the Trump hotel in Washington spent more than $900 for a stay there last year, according to a document reviewed by CNN – the first publicly known movement of federal taxpayer dollars into the highly scrutinized business.

The GSA and Trump Organization did not immediately respond to requests for comment.

CNN’s Erica Orden, Cristina Alesci and Curt Devine contributed to this report.