"If the accusations are true, then we think that he needs to resign," Bryan Fischer, the executive director of the Idaho Values Alliance, told ABCNEWS.com. "We believe that character is an important qualification for public service and we believe if these accounts are true, then the senator's conduct has fallen short of what we should expect from public officials."
Fischer, who supports the senator's anti-abortion policy and his opposition to gay marriage, said that many of his fellow Idahoans were not surprised to hear about the arrest.
"I don't think people were shocked because these rumors had circulated for years, but people in Idaho feel tremendous disappointment. You know that they feel they have been let down by another public figure. I've heard from some in our alliance, virtually everyone was aware that the rumors had circulated and they're disappointed that there might have been some fire behind that smoke," he said.
Some of Craig's former staffers reacted in disbelief, doubting accounts of the incident despite the senator's guilty plea and the police report.
"Larry Craig has integrity, is credible and I know he has done the best thing he can," former campaign aide John Keenan told ABCNEWS.com. "I do not believe the allegations and neither do the people I've talked to — current and former staffers."
Keenan worked for Craig during congressional page scandal in the early 1980s, in which two senators were censured for having sex with underage pages. Though Craig's name never surfaced in the investigation, he preemptively denied any inappropriate behavior with pages. "I can tell you his reaction was disbelief. It was a charge that was incredible, nonbelievable and he responded and asserted it was not true and that's how he conveyed it to not only his staff, but to the press," said Keenan. "I believed him then and still believe him now."
A longtime neighbor of Craig was also shocked. Ed Johnson, the openly gay assistant director of the American Humanists Association, said that Craig stays on a boat next to Johnson's marina.
"I've known Larry socially for about 10 years, maybe, it's been awhile. It's hard for me to imagine [the rumors]," said Johnson. "I work for a very progressive organization and I'm a very liberal gay man. I wouldn't hesitate to out him if I've ever heard anything. It's just hard for me to imagine."
Craig's spokesman, Sidney Smith, said it was uncertain late Monday if Craig's guilty plea would affect his re-election plans. "It's too early to talk about anything about that," Smith said.
A political science professor in Idaho said Craig's political future was in jeopardy and Hannah August, a spokesman for the Democratic Senate Campaign Committee, said Craig's guilty plea "has given Americans another reason not to vote Republican" next year.
Earlier today, liberal action group Citizens for Responsibility and Ethics in Washington filed a complaint against Craig with the Senate Ethics Committee, asking the panel to investigate whether the lawmaker had violated the Senate Rules of Conduct by pleading guilty to disorderly conduct.
"If pleading guilty to charges stemming from an attempt to solicit an undercover officer in a public restroom is not conduct that reflects poorly upon the Senate, what is?" asked CREW's executive director, Melanie Sloan.
Craig said in a statement issued by his office Monday that he was not involved in any inappropriate conduct.