Sen. John Ensign (Nev.) used Tuesday’s weekly Republican policy luncheon to lobby his colleagues on health care reform — even as he faced a new round of accusations stemming from his affair with a former campaign staffer. But outside cloistered Senate meeting rooms, Ensign launched a very public campaign to defend himself and bat down calls for his resignation.

Ensign’s decision to publicly talk about the scandal runs counter to the low-profile “Vitter strategy— that he had been following since he acknowledged the affair earlier this year. Named after Sen. David Vitter’s (R-La.) approach to the fallout from his own sex scandal, the strategy requires that the Member, after making a public admission of his actions, maintain a low public profile for a period of time before returning to a public-business-as-usual routine — while using private meetings with colleagues to make amends and seek support.

Vitter’s strategy was remarkably successful: After remaining out of the public eye for several months, he slowly worked his way back into a normal routine in the Senate, and he used the weekly luncheons to address his colleagues’ concerns and to ask for forgiveness.

Ensign seemed to be following in Vitter’s footsteps, until his decision Tuesday to openly engage the media on the scandal.

In an interview with CNN, Ensign denied charges that his efforts on behalf Doug Hampton — his mistress’s husband and a former top aide in Ensign’s personal office — violated the chamber’s ethics rules.

“We absolutely did nothing except for comply exactly with what the ethics laws and the ethics rules of the Senate state. We were very careful in everything that we did, and you can see our statements on that,— Ensign said.

Hampton — backed up by e-mails and documents — told the New York Times that he and Ensign knowingly violated the chamber’s one-year ban on lobbying by retiring staff, that Ensign pushed his donors to hire Hampton and that Ensign and his staff subsequently gave those clients legislative favors.

Ensign flatly denied that he conspired with Hampton. “I never met with Doug Hampton about any of that stuff,— Ensign said.

Ensign also told CNN that he will cooperate with the Ethics Committee investigation into the scandal, as well as any federal investigation. “We are going to cooperate with any official inquiries,— he said.

Senate Ethics Chairman Barbara Boxer (D-Calif.) acknowledged over the weekend that her panel has launched a preliminary investigation into the Ensign matter, and ethics experts have said Ensign will almost certainly face some sort of investigation by the Justice Department.

Despite the growing attention to the scandal — and the potential for a criminal inquiry being started by DOJ — Ensign told reporters Tuesday that he will not resign. “I fully plan on working and staying in office,— Ensign said.

Sen. Tom Coburn (R-Okla.), a close friend of Ensign’s who counseled his colleague during the affair while the two men lived together in a group house, said Tuesday that he would cooperate with the Ethics Committee inquiry. “I kind of look forward to a good investigation,— Coburn said.

Coburn also acknowledged discussing the investigation with Ensign, but he declined to comment on the specifics of his conversations with the embattled lawmaker.

“Well, I’ve talked with John. I don’t have anything to say about our private conversations,— Coburn said.

Sen. Jim DeMint (R-S.C.) — who also lives in the same group house with Coburn and Ensign but did not know about the affair — said that while Republicans are unhappy with Ensign, the latest revelations have not weakened his position in the Conference.

“We are very disappointed. But he’s apologized and said he’s sorry to the Conference,— DeMint said, adding that he’ll reserve judgment until the ethics investigation is over. “I’m just going to let the whole thing fall as it will.—