PHOENIX — Jared Loughner on Monday pleaded not guilty to charges that he tried to assassinate U.S. Rep. Gabrielle Giffords and two members of her staff in the course of a shooting rampage that killed six people.

Lougher entered the federal courtroom in an orange jumpsuit and sporting a very broad, pleased smile. He chortled as his defense attorney, Judy Clarke, spoke with him.

The arraignment Monday afternoon was Loughner’s second court appearance since the Tucson shooting spree on Jan. 8. Federal prosecutors have previously charged him with murder but are rolling out new indictments via the grand jury so they can avoid revealing their evidence at a preliminary hearing.

The 22-year-old Loughner could face the death penalty for the shooting because those killed included one of Giffords’ staff and the presiding judge of the federal courthouse in Tucson. All Arizona federal judges have recused themselves, and the judge hearing the case, Larry A. Burns, has traveled to Phoenix from San Diego.

In the days after the shooting, the case was moved from Tucson to the courthouse Phoenix. But federal prosecutors are seeking to move subsequent hearings back to Tucson to make it easier for victims of the attack to witness proceedings.

Giffords continued on Monday to recuperate at a Houston hospital linked to a nationally known rehabilitation center. The hospital said on Sunday she was improving but would remain in the intensive care unit for the time being.