President Trump and his business on Monday sued House Oversight Committee Chairman Elijah E. Cummings (D-Md.) in a bid to block a congressional subpoena of his financial records.

The lawsuit seeks a court order to prevent Trump’s accounting firm from complying with what his lawyers say is an improper use of subpoena power by congressional Democrats.

“Democrats are using their new control of congressional committees to investigate every aspect of President Trump’s personal finances, businesses, and even his family,” the filing by Trump claims. “Instead of working with the President to pass bipartisan legislation that would actually benefit Americans, House Democrats are singularly obsessed with finding something they can use to damage the President politically.”

The filing, in the U.S. District Court for the District of Columbia, further escalates a clash between the White House and the Democratic House over congressional oversight.

Last week, Cummings subpoenaed Mazars USA, an accounting firm long used by Trump.

For more than a decade, Mazars and a predecessor firm signed off on financial statements for Trump that he used when seeking loans. Some of the statements include frequent exaggerations or inaccuracies and were accompanied by a note from the firm saying it was not responsible for the accuracy of the information.

The Oversight committee on March 20 asked the company for copies of “statements of financial condition” and audits prepared for Trump and several of his companies, including the one that owns the Trump International Hotel in downtown Washington. The panel also requested supporting documents used to produce the reports and communications between the firm and Trump.

The company said last week that it “will respect the legal process and fully comply with its legal obligations.”

Lawyers for the president and the Trump Organization previously wrote in a letter to Mazars’ counsel that an expected committee subpoena “would not be valid or enforceable.”