Responding to backlash from the influence industry, House negotiators will go into conference prepared to further scale back the lobbying bill passed last month.

Destined for dilution is a provision that would prohibit lobbying work by law firms with attorneys under contract to congressional offices.

The prohibition was inspired by the House Judiciary Committee’s contract with Irv Nathan, a partner at Arnold and Porter, a major Washington law firm. Nathan has been hired at a rate of up to $25,000 a month to advise the committee on its investigation of the firing of U.S. attorneys.

The House passed its version of the lobbying bill (HR 2316) on May 24; the Senate passed its bill (S 1) in January. House and Senate leaders say they want to finish a conference quickly, but they have yet to name conferees.

Democrats did not object when the House Judiciary Committee added the provision sponsored by Chris Cannon, a Utah Republican, on a voice vote during a May 17 markup.

Cannon’s language would prevent law firms from lobbying while their attorneys are working for congressional offices or committees, and for a year after such contracts ended.

Cannon said he will agree to narrow the provision so that it would not apply to legal representation of lawmakers that is paid for with campaign contributions or personal funds. That would spare law firms that represent congressional clients with legal troubles.

But some lobbyists and law firms want negotiators to limit the lobbying prohibition to the individual lawyers working for Congress rather than apply the ban to whole firms. Representatives of Patton Boggs, the biggest lobbying firm in Washington, have met with House members to lobby for scaling back the provision.

“The whole point is, they don’t want [Irv Nathan] to go back and lobby Judiciary,” said Brian Pallasch, president of the American League of Lobbyists. “But the way it’s written, it could capture all these folks. You’re talking about firms with hundreds of lawyers. It casts a rather wide net.”

Nathan’s contract with the Judiciary Committee could jeopardize the work of Arnold and Porter’s dozens of registered lobbyists, who collected $1.2 million in lobbying fees during the first half of 2006, according to Congressional Quarterly’s Political Money Line.

According to a Judiciary Committee spokeswoman, House ethics rules already prohibit Arnold and Porter from lobbying the committee or its members while Nathan is under contract.

Cannon is not interested in limiting the lobbying ban to individual attorneys working with congressional offices. The point of his proposal is to avoid a conflict of interest that could arise when a law firm lobbies Congress while one of its employees is working for congressional offices.

Cannon is also apparently concerned about Congress’ use of outside legal counsel.

“The crux of this is, you’re paying outside lawyers to do the work of congressional staff,” said Cannon spokesman Fred Piccolo. “Congress has to choose whether to pay staff or contract out everything.”

The practice of hiring outside experts for professional advice is somewhat unusual. The $25,000-a-month cost is much more than lawmakers or aides are paid.

Earlier this year, House Majority Whip James E. Clyburn, a Democrat representing South Carolina, banned Microsoft Corp. from lobbying his office while he temporarily employed a former Microsoft employee. That aide, Matt Gelman, worked on a short-term basis for Clyburn, who wanted to tap his experience as part of the whip operation of former Rep. David E. Bonior, D-Mich. (1977-2001).