Senate grills Secret Service on potential âpattern of misconduct Mark Sullivan, director of the U.S. Secret Service, defended his agency on Wednesday against accusations it has displayed a "pattern of misconduct" during a Senate hearing prompted byÂ a recent scandal involving agent solicitation of prostitutes in Columbia. This is "not a systemic problem," Sullivan told members of the Senate Homeland Security and Governmental Affairs Committee. Sullivan stressed multiple times during the two-hour hearing that the overwhelming majority of agency employees are ethical and uphold the standards of their job. The incidents referenced in the hearing are "not representative of these values or the high ethical standards we demand," Sullivan said, adding, "I am deeply disappointed and apologize for the misconduct" of the employees involved. Sullivan encouraged members of Congress to continue supporting the agency during this "difficult" period, and to let employees "know that we have confidence in them and believe in them and know this is not indicative of their character." But Senators repeatedly questioned Sullivan's assertions, noting that in addition to last month's scandal in which 12 members of the president's Secret Service advance team were connected to the solicitation of prostitutes in Cartagena, Columbia, some of the agents who were dismissed have raised further questions. The Washington Post reported on Wednesday that four agents who are disputing their dismissals now say that unethical behavior is tolerated, and they cited other incidents, including one in San Salvador, that could be marked as misconduct. "This likely was not just a one-time incident," ranking Sen. Susan Collins of Maine told Sullivan and Charles K. Edwards, acting inspector general for the Homeland Security Department, who also testified. Collins observed that two of the 12 individuals involved in the Columbia incident were supervisors and married men. "That certainly sends a message to the rank and file" that this type of activity "is tolerated on the road," Collins said. Collins added that the employees did not conceal their identities when registering at the hotel with the prostitutes, suggesting the agents involved knew their behavior would be tolerated. Additionally, Collins suggested that Sullivan's own untarnished 28 years of service in the agency is clouding his assessment of the situation. Because Sullivan personally didn't see this type of misconduct, Collins said she could understand why it was "very difficult for [him] to accept that this happened." "I urge you to try to put that aside," she said. I believe the problem is broader than you believe it to be. Committee Chairman Joe Lieberman (I-Conn.) did not go as far his colleague, saying that while the individual cases are deeply troubling, the committee has found no evidence of a "pattern of misconduct." During the course of the hearing Wednesday, Sullivan revealed that the agency had previously conducted an internal survey which found that only 58-60 percent of employees would report ethical misconduct. Republican Sen. Ron Johnson of Wisconsin, Collins and other committee members questioned why those results were not a serious cause for concern for the agency. "We want to improve that number to 100 percent," Sullivan responded during a grilling from Johnson. He later explained to Collins that the survey found 18 to 19 percent of respondents said they would not report misconduct and the remaining respondents were "indifferent." Throughout the hearing, senators decried the scandal as harmful to the Secret Service's reputation. Swift action was needed to "clean the wound," Lieberman said, as well as to ensure that protection of the president, presidential candidates and others is not compromised. Sullivan said that in addition to launching its own investigation of the Columbia situation and placing all 12 of the employees involved on leave and suspending their security clearances, the agency has established a "professional reinforcement working group" to review the agency's practices, training, personnel management and other functions of the agency as it relates to ethics. Edward is heading up a review of the Secret Service's handling of its internal investigation. Collins stressed that the review must be completely independent of the agency, a directive Lieberman seconded. The committee instructed Edwards to add sufficient staff to his team to expedite their review, which senators said they hope will be concluded this summer. â¢Â Obama aides gave Hollywood team rare CIA, Pentagon access on bin Laden raid info â¢Â Pakistani doctor who helped CIA find Osama bin Laden jailed for treason â¢Â Sarah Palin endorses Sen. Orrin Hatch in Utah VisitÂ The Ticket or connect with usÂ on Facebook, follow us on Twitter, or add usÂ onÂ Tumblr.