A federal judge in Washington, D.C., has ruled President Donald Trump’s longtime accounting firm must turn over years of his financial records to the U.S. House of Representatives, upholding a Congressional subpoena that demanded those documents.

The ruling from U.S. District Judge Amit Mehta delivered a major blow to Trump in what marks the first time a federal court has waded into the continued standoff between the president and Democratic lawmakers. Lawyers for Trump filed the lawsuit last month seeking to block his accountant, Mazars USA LLP, from complying with a House Oversight committee’s subpoena.