House Democrats asked a U.S. court to force the Treasury Department to turn over six years of President Donald Trump's personal and business tax returns.

The long-expected lawsuit filed Tuesday is the latest attempt by Congress to assert oversight over the executive branch, as the Trump administration has either rejected or ignored various subpoenas since Democrats took the majority in the House in January.

"In refusing to comply with the statute, defendants have mounted an extraordinary attack on the authority of Congress to obtain information needed to conduct oversight of Treasury, the IRS, and the tax laws on behalf of the American people who participate in the nation's voluntary tax system," the complaint said.