NEW YORK (Reuters) -Manhattan District Attorney Alvin Bragg on Tuesday sued Republican U.S. Representative Jim Jordan to stop what Bragg called an “unconstitutional attack” on the ongoing criminal prosecution of former President Donald Trump in New York.

The lawsuit aims to block a subpoena of Mark Pomerantz, a former prosecutor who had led the Manhattan district attorney’s investigation of Trump. The subpoena, issued last week by the House of Representatives Judiciary Committee, which Jordan chairs, seeks Pomerantz’s appearance before the committee for a deposition.

Trump, a Republican, pleaded not guilty last week to charges brought by Bragg’s office of falsifying business records to conceal a hush money payment made ahead of the 2016 election to buy a porn star’s silence about an affair she said she had with Trump.

Bragg, a Democrat, accused congressional Republicans of an “incursion” into a state criminal case.

“Members of Congress are not free to invade New York’s sovereign authority for their or Mr. Trump’s political aims,” Bragg’s office wrote in the lawsuit, accusing Jordan of searching for a pretext for “hauling Mr. Pomerantz to Washington for a retaliatory political circus.”