Donald Trump sued Manhattan District Attorney Cyrus Vance Jr. as New York state prosecutors seek eight years of the president’s tax returns in a probe of whether the Trump Organization falsified business records.

“In response to the subpoenas issued by the New York County District Attorney, we have filed a lawsuit this morning in federal court on behalf of the President in order to address the significant constitutional issues at stake in this case,” Jay Sekulow, the president’s lawyer, said in a statement.

The suit was filed Thursday in Manhattan federal court and also names Mazars USA, Trump’s longtime accounting firm. A copy of the complaint wasn’t immediately available.

Vance opened the investigation last month and filed the subpoenas late last month, The New York Times reported on Sept. 17. It focuses on payments that Trump’s former personal lawyer, Michael Cohen, made before the election to adult film star Stormy Daniels, the paper said.

This story was provided by Bloomberg News.