DENVER -- A woman who admitted starting the worst wildfire in Colorado's recorded history has appealed a judge's ruling that said prosecutors could withdraw from her plea agreement, possibly leading to a new trial -- and a longer prison term.

Colorado's Supreme Court has ordered prosecutors to explain why they believe the ruling should stand.

The appeal by the attorney for Terry Lynn Barton, filed last week, prompted Teller County District Judge Thomas Kennedy to reschedule a Monday hearing set to discuss the possibility of a new trial.

Kennedy ruled Feb. 5 that Barton violated terms of her plea agreement when she appealed her 12-year prison sentence, opening the way for prosecutors to withdraw the agreement. Prosecutors have been deciding whether to ask for a new trial or a new sentencing hearing for Barton, who is serving a 6-year federal prison term for setting the June 2002 Hayman fire.

The Supreme Court gave prosecutors until April 9 to file arguments supporting Kennedy's ruling.

In Barton's appeal, Deputy Public Defender Mark Walta wrote that Kennedy abused his discretion and exceeded his authority when he said prosecutors could withdraw the agreement. He said if the ruling were allowed to stand, it would undermine the public's trust in the court system.

"This court has repeatedly rejected efforts on the part of the prosecution to withdraw from accepted plea agreements merely because the defendant has been granted some reduction in her sentence," Walta wrote. "It leaves the impression that prosecutors may circumvent both the judgment of our appellate courts and the commands of the law by withdrawing from plea agreements that they no longer regard as favorable."

In his filing, Walta said there was nothing in Barton's plea agreement that prevented her from appealing what she considered an illegal sentence. He said it would be unfair to expose her to the possibility of facing new trials in four separate counties affected by the fire.

Walta declined further comment. El Paso County District Attorney John Newsome, who represents his district and three others affected by the fire for the Barton case, did not immediately return a call.

Barton pleaded guilty to state and federal arson charges after admitting she set the fire by burning a letter in a drought-stricken area during a ban on fires. Barton was employed by the U.S. Forest Service to look for people violating the fire ban.

She is serving a 6-year federal sentence. The Colorado Court of Appeals threw out her 12-year state sentence. Barton also was ordered to pay $42.2 million in state and federal restitution.

The fire scorched 138,000 acres, destroyed 133 homes and forced more than 8,000 people to leave their homes.