Under pressure from a newspaper investigation, Sen. Larry Craig "panicked" and pleaded guilty to disorderly conduct in a Minneapolis-St. Paul International Airport men's room, according to court papers filed Monday.

The plea constitutes a "manifest injustice" and should be set aside, his lawyers say.

The 50-page filing in Hennepin County District Court said Craig feared his arrest in the airport sting would prompt the Idaho Statesman to publish a story examining his sexual orientation. The Republican, who has represented Idaho in the U.S. Senate for 17 years, "felt compelled to grasp the lifeline offered to him by the police officer, namely that if he were to submit to an interview and plead guilty, then none of the officer's allegations would be made public," the filing said.

Craig pleaded guilty by mail to disorderly conduct in August following his arrest in June. A police report alleged that Craig had solicited sex from police Sgt. Dave Karsnia, which the senator has denied.

After Craig's arrest was made public, the Idaho Statesman published its five-month investigation into previous allegations of homosexual behavior. Craig said he is not gay.

Statesman editor and vice president Vicki Gowler defended the newspaper's investigation. "From the start, it was important to us to do a thorough and responsible investigation, outside of deadline pressures. We did that," Gowler said.

Airport will fight petition

Craig has said he intended to resign Sept. 30, but he has also acknowledged that if he can withdraw his guilty plea, he will keep open a small window to stay in office through the remainder of his term.

A hearing date and judge for the petition have not been set.

Patrick Hogan, spokesman for the Metropolitan Airports Commission, said, "We will file an objection to the senator's motion and defend our case vigorously in court."

Prominent defense lawyers in Hennepin County say Craig may have trouble making the case, but at least two say he should have a day in court. In addition, a land rights group is calling for a boycott of the airport in support of Craig.

In submitting his plea by mail, Craig never appeared in court and was never questioned by a judge. "Craig is not a lawyer and, like any other non-lawyer, should not be expected to understand the intricacies of constitutional law," the petition said.

If a judge had spoken with Craig, "the court would have quickly concluded that, faced with the pressure of an aggressive interrogation and the consequences of public embarrassment, Senator Craig panicked," the petition said.

Craig's lawyers also argued that the evidence is insufficient to support a guilty plea to disorderly conduct, defined by state law as "offensive, obscene, abusive, boisterous, or noisy conduct or ... offensive, obscene, or abusive language tending reasonably to arouse alarm, anger or resentment in others."

Karsnia merely observed "several ambiguous -- but legal -- hand and foot gestures," the petition said.

What defense lawyers think

Twin Cities attorney Michael Colich said the argument that Craig made a mistake "probably isn't going to warrant withdrawal of the plea. ... Countless people after they plead guilty have second thoughts."

Colich said he has successfully withdrawn pleas for clients who had been poorly represented by lawyers. "They certainly didn't have the same background as Senator Craig."