U.S. Sen. Larry Craig of Idaho appealed to the Minnesota Court of Appeals on Monday in his ongoing attempt to withdraw his guilty plea in connection with an arrest in an airport bathroom sex sting.

Craig's appeal was filed at the court in St. Paul less than two weeks after Hennepin County Judge Charles Porter refused to overturn the guilty plea, saying it "was accurate, voluntary and intelligent, and ... supported by the evidence."

Craig, a Republican, pleaded guilty to disorderly conduct in August after he was accused of soliciting sex in a bathroom at the Minneapolis-St. Paul International Airport in June.

The four-page filing did not detail the basis for the appeal.

In an interview on Sunday with KTVB-TV in Boise, Idaho, Craig repeated he will not resign his post in the Senate and said he had the right to pursue his legal options.

"It is my right to do what I'm doing," said Craig. "I've already provided for Idaho certainty that Idaho needed — I'm not running for re-election. I'm no longer in the way. I am pursuing my constitutional rights."

But legal experts have predicted Craig would have a hard time winning on appeal.

"What's the likelihood of success? Even less likely of prevailing in the appeal than he had in prevailing before Porter," Steve Simon, a legal defense expert at the University of Minnesota Law School, said earlier this month.

The appeals court must find there's been an "abuse of discretion" by the trial judge before overturning a ruling — in other words, that some aspect of the ruling was decided improperly. Ron Meshbesher, a longtime Minneapolis defense attorney, said earlier this month that the standard for an abuse of discretion is vague but that such a ruling is fairly rare.

"It's not frequent, let's put it that way," Meshbesher said. "It certainly is a steep hill to climb."

It would most likely be well into 2008 before the Court of Appeals rules on the case. The process by which both sides prepare their legal briefs alone usually stretches to more than 100 days.

A heavy caseload at the Court of Appeals has slowed down both the scheduling of oral arguments and the release of rulings, according to court spokesman John Kostouros. It's been taking at least three months after briefs are filed for arguments to be scheduled, he said, and at least another three months before a decision is reached.

Craig's Senate term ends at the end of 2008.