Sen. Larry Craig will file court documents Monday asking to withdraw his guilty plea in a sex sting that seems likely to end his career, his attorney said.

Craig, an Idaho Republican, pleaded guilty in August to disorderly conduct following a sting operation in a men's bathroom at the Minneapolis airport.

He has said he regrets that decision, which he said he made hastily and without talking to an attorney. He said he was under stress and pleaded guilty only to put the matter behind him.

Attorney William Martin said Sunday night that a request to withdraw that plea would be filed Monday. Such requests are rarely granted. Martin would not discuss the argument he planned to make in court.

Martin said he was not involved in discussions about Craig's future in the Senate. Craig originally announced he would resign at the end of the month, then said he was reconsidering that decision. His chief spokesman later said Craig had dropped virtually all notions of trying to finish his third term.

"My job is to get him back to where he was before his rights were taken away," Martin said.

Craig's congressional spokesman has said the only way that Craig is likely to remain in the Senate is if a court moves quickly to overturn the conviction, something that is unlikely to happen before the end of the month.

But Judy Smith, a spokeswoman for Craig's legal team, said the lawyers are focused only on the Minnesota case, not political outcomes.

Many Republicans have urged Craig to say for sure that he will resign. That would spare the party an ethics dilemma and the embarrassment of dealing with a colleague who had been stripped of his committee leadership posts.

It also would negate the need for a Senate ethics committee investigation, which GOP leaders had requested.

If Craig succeeds in undoing his plea, he would likely try to have the charges dismissed to avoid an embarrassing trial.

A police report alleged that Craig had solicited sex from a male officer at the Minneapolis airport in June.

Appearing on CNN's "Late Edition," Sen. Arlen Specter, R-Pa., said Craig is entitled to his day in court.

"Maybe he'll be convicted, but I doubt it," said Specter, the Senate Judiciary Committee's ranking Republican.

Specter said that when he learned the details of the arrest "I was convinced that he couldn't be convicted if he fought the case."

Minnesota law is that a guilty plea may be withdrawn if it was not intelligently made "and what Sen. Craig did was by no means intelligent," said Specter.