Sen. Larry Craig is no doubt pondering his future on Tuesday.

The Idaho Republican has been debating whether to prolong his 27-year career as an elected official by running for a fourth term of office, and was expected to make an announcement next month.

Now any plans may be on hold after being arrested in June and pleading guilty this month in connection with a police sting operation of lewd conduct in a men's bathroom at the Minneapolis-St. Paul International Airport.

Liberal government watchdog group Citizens for Responsibility and Ethics in Washington filed a complaint Tuesday with the Senate ethics committee seeking an investigation into whether Craig violated Senate rules by engaging in disorderly conduct.

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

"The Senate Ethics Manual provides that certain conduct may be improper even though it does not violate specific Senate rules or regulations. Such conduct has been characterized as 'improper conduct which may reflect upon the Senate,'" CREW said in a press release. "This rule is intended to protect the integrity and reputation of the Senate as a whole."

The Senate Democratic Campaign Committee is also hoping to capitalize on the disorderly conduct misdemeanor now on Craig's record. Spokeswoman Hannah August said the guilty plea "has given Americans another reason not to vote Republican."

But while Democrats look to exploit the incident for political gain, Republicans too are saying they are displeased with the turn of events. On Monday Craig quit Mitt Romney's presidential campaign, where he was a co-chairman.

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

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.

Patrick Sammon, president of the Log Cabin Republicans, a gay Republican group, said by "his own admission," Craig violated the law, and voters should expect more from their representatives.

"Senator Larry Craig's ability to continue serving the people of Idaho is in serious doubt," Sammon said. "He has violated the public trust, not just with his inappropriate and illegal behavior, but in the subsequent explanation of his actions. Innocent people don't plead guilty. The time to contest these allegations would've been before his guilty plea."

Craig, 62, has a conservative record in the Senate — he has voted against gay marriage, opposed extending special protections to gay and lesbian crime victims and supported barring homosexuals from serving in the Boy Scouts. Craig has gone into seclusion with his family at an undisclosed location in the Boise area.

Aides say it's premature to discuss whether the scandal will affect Craig's decision whether or not to seek a fourth term in the Senate next year.

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

But this latest incident could tip the scales and end his Craig's career, 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."

Allegations that Craig is a closet homosexual have dogged him since his college days in the 1960s, according to the 3,700-word article in Tuesday's Idaho Statesman, Craig's home state newspaper.

Click here to read the Idaho Statesman article.

During Craig's first term in Congress back in the early 1980s, when House and Senate members stood accused of abusing congressional pages, Craig took the unusual step of issuing a pre-emptive denial of involvement.

The paper said it had received allegations in May from a man who said he and Craig engaged in sex at a men's bathroom in Washington, D.C.'s Union Station. Another man claimed Craig eyed him up during a half-hour cat and mouse chase in a Boise, Idaho, store in 1994.

At the time, Craig called the charges scurrilous.

"I've been in this business 27 years in the public eye here. I don't go around anywhere hitting on men, and by God, if I did, I wouldn't do it in Boise, Idaho! Jiminy!" he told the newspaper.

The years of charges and allegations remained unsubstantiated until Aug. 8, when Craig pleaded guilty in a Hennepin County, Minn. court. Craig claims he is innocent of anything untoward, but he should have consulted a lawyer rather than trying to brush the June incident under the rug. He paid a $575 fine and was given a stay on a 10-day prison sentence barring no further violations during one year of unsupervised probation.

"At the time of this incident, I complained to the police that they were misconstruing my actions. I was not involved in any inappropriate conduct," Craig said Monday. "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 was first to report the details of Craig's June 11 arrest by a plainclothes officer investigating complaints of lewd conduct in a men's restroom at the airport.

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

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