PORTLAND — The Portland man charged with sending threatening letters to Gov. Paul LePage now faces new charges of threatening to kill members of Congress.

Michael Thomas, 50, pleaded not guilty today to charges he threatened U.S. Rep. Steve King, R-Iowa, and U.S. Sen. Joe Lieberman, I-Conn., as well as LePage. Thomas also pled not guilty to a charge of being a felon in possession of a gun.

Thomas was arrested March 25 at his apartment at Loring House, a Portland Housing Authority property for senior citizens and people who have disabilities. Police used DNA from the LePage letters to identify Thomas as a suspect, according to his court file.

Authorities found a gun and an ammunition clip in Thomas’ desk drawer when he was arrested and Thomas said that if they had shown up later, he would have engaged them in a shootout, authorities said.

Thomas, who appeared in handcuffs and leg chains for a brief hearing in U.S. District Court in Portland today, remains in custody pending a trial now set for June 6.

Thomas is accused of sending LePage three letters, which said among other things that the author was willing to sacrifice his life to shoot the governor.

Although authorities alleged in an earlier hearing that he had made threats against Maine Sens. Susan Collins and Olympia Snowe and Wisconsin Gov. Scott Walker, Thomas was not charged in connection with those communications.

The grand jury indicted Thomas on Tuesday. Threatening members of Congress and possessing a firearm are punishable by up to 10 years in prison and a $250,000 fine and mailing threatening communications is punishable by five years in prison and a $250,000 fine.

The indictment says Thomas’ previous felony conviction stems from a stalking incident for which he was convicted in Lynn, Mass., in 2000.