The new ethics rules may have barred lawmakers turned lobbyists from the Senate floor, but as former Sen. Don Nickles (R-Okla.) proved last week, they still enjoy bankable access to Republicans’ backroom strategy sessions just steps from the chamber.

Nickles, who has headed his own lobbying shop since leaving the Senate in 2004, dined with Senators during their regular Wednesday Steering Committee luncheon, a meeting of conservative Senators organized by the committee’s chairman, Sen. Jim DeMint (S.C.).

While it is not clear what was discussed, the session came hours before the vote on a Senate-crafted stimulus package that offered billions of dollars in tax benefits to major corporations, including such Nickles clients as General Electric, Exxon Mobil and Anadarko Petroleum.

Nickles did not return calls, and the Steering Committee declined to comment on who is invited to participate in their weekly meetings. The weekly meetings were described by several GOP sources as “informal” gatherings, and therefore not subject to rules governing official meetings of Republican Senators.

The steering lunches are separate from the GOP’s weekly policy lunches or occasional Conference meetings, the admission policies of which appear somewhat vague. Asked Friday to describe the current Republican rules regarding ex-Senators and Conference-organized sessions, Ryan Loskarn, a spokesman for Republican Conference Chairman Lamar Alexander (Tenn.), said: “Former Members are not invited to attend Conference meetings and historically do not attend, but they are not prohibited from doing so.”

The issue of ex-Members’ attendance at weekly policy lunches came to a head two years ago, after former Sen. Lauch Faircloth (R-N.C.), a lobbyist for companies pushing an asbestos liability bill, attended a lunch hours before a vote on the measure.

In the wake of that episode, GOP Senators tightened the open-door policy. Now, a Senate leadership aide said, former lawmakers are still welcome at the sessions, but they are not permitted to lobby and are expected not to attend if they are lobbying on pending Senate business.

Nickles hardly is the first former GOP Senator now on K Street to take advantage of the privilege, even under the new ethics regime.

Former Sen. Conrad Burns (Mont.), a consultant with the lobbying firm Gage LLC, and ex.-Sen. Ben Nighthorse Campbell (Colo.), a lobbyist with Holland & Knight, also have been seen walking into an occasional Senate noontime gathering in recent months.

And in years past, a clutch of retired GOP Senators working for lobbying firms also made a practice of occasionally dropping in on the lunches, including Slade Gorton (Wash.), Rod Grams (Minn.) and Tim Hutchinson (Ark.).

But with the latest example, some on and off of Capitol Hill are calling for a re-evaluation of the policy.

Considering lawmakers turned lobbyists no longer are allowed in the chambers or Congressional gyms, Sen. Olympia Snowe (R-Maine) said that the same rules should apply throughout the Capitol.

“If [former Members] are restricted on the floor,” she argued, “they might as well be restricted elsewhere. The Senate should address it,” she said. “It’s the perception.”

Bill Allison, a senior fellow with the Sunlight Foundation, a watchdog group, called the exemption “a huge hole in the rules.”

“That’s something that should have been addressed” in lobbying reform legislation, he said. “Where would you rather be talking policy? At the gym or around a conference table?”

Senate Democrats, meanwhile, informally have imposed a prohibition on letting old colleagues come up from K Street to sit in on their weekly lunches.

Jim Manley, spokesman for Majority Leader Harry Reid (Nev.), said that while there’s no official Conference policy barring former Members from attending the Senator meetings, Reid never has allowed it under his leadership.

Asked about whether it was ever allowed, Manley said, “I don’t know. It hasn’t happened as long as Reid has been leader and it’s not going to happen in the future.”

And that’s a good thing, Sen. Bob Menendez (D-N.J.) argued, since Senators use those sessions to vet policies and outline strategies for which there should be an exclusive audience. Senators turned lobbyists shouldn’t have access to that information, he said.

“It’s not the appropriate place for former Members,” Menendez said. “And they don’t need to do that to see you. It seems to me certain caucus lunches are more than a social event, it’s a working event and in my mind, that’s inappropriate.”

Ex-Members are not allowed at House Democratic Caucus meetings either, unless they have been specifically invited, a House aide said.

But a House Republican aide said former Members are allowed to attend their weekly strategy sessions.

Some GOP Senators defended the practice.

Sen. John Thune (R-S.D.) said he believes it would be improper for former Senators to attend the lunches if they were actually using the opportunity to influence lawmakers. But, he said, “if they are there just hanging out with old friends, it doesn’t bother me.”

Thune argued that it would be “over the top to ban any interaction” between former Senators and current ones.

He added that he doesn’t believe there’s been any influence peddling at the GOP sessions, saying “it would become problematic if they were there bending arms and trying to lobby Senators on a particular issue.

“That’s not been my experience,” he said.

Sen. Richard Burr (N.C.) said it’s absurd to suggest that Senators could be so easily influenced by a former Member, charging that the new, stiffer lobbying restrictions are part of a larger “ethics trap we created that’s only being used for political purposes.”

“I’ve never been lobbied by a former Member, at best I remember, at a lunch or even in my office,” he said. “We were trying to address a problem that didn’t exist.”