Promising "you haven't seen the last of me," a 70-year-old disbarred lawyer convicted in a terrorism case surrendered to U.S. marshals Thursday to begin serving her prison term after a New York appeals court upheld her conviction.

A smiling Lynne Stewart walked with several dozen supporters to a collection of cameras on her way into U.S. District Court in Manhattan on Thursday, shaking a fist in the air to chants of "Free Lynne Stewart."

"It's very hard to feel downhearted today," she said. "I can take whatever they dish out. I am not going to back off ever."

Stewart said she would become a jailhouse lawyer to the extent her disbarment will allow, helping other inmates with their legal fights.

Stewart was ordered a day earlier to begin serving her two-year, four-month sentence. She was convicted in 2005 of charges that she let a Muslim extremist client convicted in a plot to blow up New York City landmarks communicate with followers. She was sentenced in 2006.

The 2nd U.S. Court of Appeals in Manhattan on Tuesday upheld the conviction and rejected a request just minutes before she entered the courthouse Thursday to further delay her incarceration. She had been free on bail pending appeal.

As soon as she heard her last chance to stay free was taken away, she announced to the crowd: "OK. We're going to prison folks."

The appeals court had also directed Stewart's sentencing judge to consider whether she should receive a harsher sentence after determining whether she lied to the jury during her trial.