Updated

Idaho Sen. Larry Craig's political future is now on much shakier ground following news that he was arrested and then pleaded guilty in connection with a police sting operation of lewd conduct in a men's bathroom.

Craig, 62, is a Republican with a conservative record — he has voted against gay marriage and opposed extending special protections to gay and lesbian crime victims. He is up for re-election next year, and has not announced whether he will run for a fourth term.

Craig spokesman Sidney Smith on Monday declined to speculate about the plea's effect on Craig's political career.

"It's too early to talk about anything about that," Smith said.

Craig was arrested in June and entered a plea to a misdemeanor charge of disorderly conduct earlier this month in a Hennepin County, Minn., court. The incident occurred at the Minneapolis-St. Paul International Airport.

• Click here to read the police report for Sen. Larry Craig.

Democrats already are taking the news as a boost in 2008.The guilty plea "has given Americans another reason not to vote Republican," said Hannah August, a Democratic Senate Campaign Committee spokeswoman.

Craig, who is married and has three children, has diffused rumors about his sexual behavior since the 1980s, including a rumor last year that he was gay. He was a member of the House for 10 years before winning election to the Senate in 1990.

But this latest incident could tip the balance, said Jasper LiCalzi, a political science professor at Albertson College of Idaho in Caldwell, Idaho.

LiCalzi cited the House page scandal that drove Florida Rep. Mark Foley from office.

"There's a chance that he'll resign over this," LiCalzi said. "With the pressure on the Republican party, he could be pressured to resign. If they think this is going to be something that's the same as Mark Foley — the sort of 'drip, drip, drip, there's more information that's going to come out' — they may try to push him out."

On Monday, Craig quit Mitt Romney's presidential campaign, shortly after the Capitol Hill newspaper Roll Call revealed the plea and arrest details.

"Sen. Craig has stepped down from his role with the campaign. He did not want to be a distraction and we accept his decision," Matt Rhoades, communications director for the Romney campaign, said.

Craig has been one of Romney's top Senate supporters, serving as a Senate liaison for the campaign since February.

A former staffer called Craig's behavior stupid and selfish.

"I am disappointed by how he dealt with the situation," the staffer, who worked for Craig for a number of years, told FOX News.

J. Kirk Sullivan, chairman of the Idaho Republican Party, declined to comment on the situation, saying he was unaware of the nature of the charges against Craig.

Details From the Airport

Roll Call reported that Craig was arrested June 11 by a plainclothes officer investigating complaints of lewd conduct in a men's restroom at the airport.

Craig pleaded guilty Aug. 8 to a misdemeanor disorderly conduct charge after being arrested at the Minneapolis airport, Hennepin County court documents showed. The court dismissed a charge of gross misdemeanor interference to privacy.

The court docket said the senator paid $575 in fines and fees. He was put on unsupervised probation for a year. A sentence of 10 days in the county workhouse was stayed.

Craig said Monday in a statement issued by his office that he was not involved in any inappropriate conduct.

"At the time of this incident, I complained to the police that they were misconstruing my actions," he said. "I should have had the advice of counsel in resolving this matter. In hindsight, I should not have pled guilty. I was trying to handle this matter myself quickly and expeditiously."

Roll Call, citing the report, said Sgt. Dave Karsnia made the arrest after an encounter in which he was seated in a stall next to a stall occupied by Craig. Karsnia described Craig tapping his foot, which Karsnia said he "recognized as a signal used by persons wishing to engage in lewd conduct."

Roll Call quoted the Aug. 8 police report as saying that Craig had handed the arresting officer a business card that identified him as a member of the Senate.

"What do you think about that?" Craig is alleged to have said, according to the report.

Just last fall, Craig called allegations from a gay rights activist that he's had homosexual relationships "completely ridiculous." Mike Rogers, who bills himself as a gay activist blogger, published the allegations on his Web site in October 2006.

Craig's whereabouts have been kept close to the vest. Smith, the Craig aide in Boise, said Monday afternoon that the senator was "in the (Boise) area" but was declining to give interviews.

The Associated Press contributed to this report.

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