The House Ways and Means Committee filed a lawsuit Tuesday to quickly enforce its subpoena for President Donald Trump’s tax returns, calling the government’s refusal to turn over the records “an extraordinary attack” on congressional oversight.

The lawsuit in federal district court in Washington is the first legal action from House Democrats to enforce a subpoena among the numerous investigations into the Trump administration launched since taking control of the chamber in January.

[Trump’s tax return battle will be fought in court, Mnuchin says]

The government has declined to comply with Chairman Richard E. Neal’s subpoena that seeks six years of the president’s personal tax returns and six years of returns from eight of the companies that he owns.

Democrats have leaned on a 1976 statute enacted in the wake of the Watergate revelations that requires the Treasury Department to provide “any” tax return requested by the Ways and Means chairman in writing, and in the lawsuit they stress congressional oversight power.