A Democratic congressman accused former US president, Donald Trump, in a federal lawsuit on Tuesday of inciting the deadly insurrection at the U.S. Capitol and of conspiring with his lawyer and extremist groups to try to prevent the Senate from certifying the results of the presidential election he lost to Joe Biden.

The lawsuit from Mississippi’s Rep. Bennie Thompson, chairman of the House Homeland Security Committee, is part of an expected wave of litigation over the Jan. 6 riot and is believed to be the first filed by a member of Congress It seeks unspecified punitive and compensatory damages.

The case also names as defendants the Republican former president’s personal lawyer Rudy Giuliani and groups including the Proud Boys and the Oath Keepers, extremist organizations that had members charged by the Justice Department with taking part in the siege.

Lawyers for Trump have denied that he incited the riot. A Trump adviser didn’t immediately comment about the lawsuit on Tuesday, and a lawyer for Giuliani did not immediately return an email seeking comment.

The suit, filed in federal court in Washington under a Reconstruction-era law known as the Ku Klux Klan Act, comes three days after Trump was acquitted in a Senate impeachment trial that centered on allegations that he incited the riot, in which five people died. That acquittal is likely to open the door to fresh legal scrutiny over Trump’s actions before and during the siege.

Even some Republicans who voted to acquit Trump on Saturday acknowledged that the more proper venue to deal with Trump was in the courts, especially now that he has left the White House and lost certain legal protections that shielded him as president.

The suit traces the drawn-out effort by Trump and Giuliani to cast doubt on the election results even though courts across the country, and state election officials, repeatedly rejected their baseless allegations of fraud. Despite evidence to the contrary, the suit says, the men portrayed the election as stolen while Trump “endorsed rather than discouraged” threats of violence from his angry supporters in the weeks leading up to the assault on the Capitol.