His actions in an airport bathroom led to a new word – toe-tapping – entering the lexicon of euphemisms for gay.

Now lawyers for embattled US Senator Larry Craig are asking for his conviction for cruising offences to be struck down because the undercover police officer who arrested him initiated the now-infamous foot signal.

Senator Craig was arrested on June 11th by an undercover police officer in a Minneapolis airport men’s room, who said the Idaho politician had engaged in conduct “often used by persons communicating a desire to engage in sexual conduct.”

This included tapping his toes and placing his hand palm upwards under a toilet cubicle, both cruising signals.

Minutes later he was arrested for disorderly conduct.

Craig denied soliciting for sex, saying “I’m not gay. I don’t do these kinds of things,” according to an audio tape released by police.

He denied that he had used foot and hand gestures to signal interest in a sexual encounter.

Despite a pledge to resign, he later announced he would challenge his guilty plea and claimed that he admitted to the charge in a panic to avoid triggering a story about his sexuality in his hometown newspaper.

“It was a very, very big mistake,” he said of his decision to plead guilty.

“I sought no counsel. I made a very big mistake.”

His lawyers are now giving the case due consideration and yesterday they lodged a 96-page brief with the Minnesota Court of Appeals explaining why they think the charges should be thrown out.

They argue that his actions fall short of the definition of disorderly conduct, and that the ‘signals’ were initiated by the arresting officer.

“First, disorderly conduct, by statutory definition, must affect ‘others.’ It is not sufficient that a single person, in this case Sgt. Karsnia, be affected,” the lawyers brief said according to twincities.com

“Sgt. Karsnia invited the alleged intrusion.”

A spokesman for the Metropolitan Airports Commission told twincities.com:

“Facts are resilient, and Senator Craig’s continued transparent efforts to escape them don’t change the truth of his behaviour in an airport restroom, or the fact that he admitted guilt last August.

“A Hennepin County district judge ruled that the Senator’s guilty plea was accurate, voluntary, intelligent and supported by the evidence. We are confident the plea will stand.”

In the wake of the bathroom scandal Senator Craig has faced tough questions about his sexuality.

In December his hometown newspaper published detailed accounts from four men of sexual encounters with him.

One of the men, Mike Jones, is a male prostitute who brought the career of homophobic preacher Ted Haggard to an end by revealing they had a sexual relationship – he made his claims about the Senator in October.

“David Phillips is a 42-year-old information technology consultant in Washington, DC who says Craig picked him up at a gay club in 1986 and that they subsequently had sex,” reported The Idaho Statesman.

“Greg Ruth was a 24-year-old college Republican in 1981 when he says he was hit on by Craig at a Republican meeting in Coeur d’Alene.

“Tom Russell, now 48, is a former Nampa resident who lives in Utah. Russell said his encounter with Craig occurred at Bogus Basin in the early 1980s.

“A fifth gay man, who is from Boise but who declined to be named for fear of retaliation, offered a recent and telling account.

“He was in a men’s restroom at Denver International Airport in September 2006 when the man in the next stall moved his hand slowly, palm up, under the divider.

“Alarmed, the man said he waited outside the restroom and then identified the man in the adjoining stall as Craig, whom he had met in Idaho.”

The Idaho Statesman said that four of the men were willing to go on record about their encounters and that the paper has carried out “reviews of travel and property records and background checks on all five men.”

In a statement Senator Craig said:

“Like its previous coverage, these latest allegations are completely false and have no basis in reality. I won’t let this paper’s attempt to malign my name stop me from continuing my work to serve the people of Idaho.”

Senator Craig has been denying he is gay since 1982, when he issued a statement saying he was not involved in a scandal over gay sex between Congressmen and underage pages, despite the fact that he had not been publicly implicated. He married a year later.

In October, appearing on TV alongside his wife, the 62-year-old Republican politician was asked by NBC correspondent Matt Lauer: “Are you technically not a homosexual?

“Is it possible you’re bisexual?”

The Senator replied: “It’s no to both.”

Mrs Craig was also questioned by Mr Lauer about her husband’s sexuality.

She admitted she did some “soul searching” after she found out about the bathroom incident, but said:

“I honestly believe my husband has always been faithful to me in every way.”

Asked about his hostile voting record on gay rights, he said: “I don’t approve of the lifestyle.”

He first announced he intended to resign by September 30th, then said he was reconsidering.

He later said he would wait until after his appeal against his guilty plea was heard.

Senator Craig then announced that despite the court decision against him he will remain in the Senate until the end of his term – another 18 months.

He was a member of the House of Representatives before winning his first Senate term in 1990.

Meanwhile ‘toe-tapper’ has been voted one of the words of 2007 by the American Dialect Society.