Senate Republicans have quietly slipped an obstacle in the path of the Clinton administration's threat to file a massive lawsuit against the tobacco industry, and several Democrats vowed yesterday to fight to remove the roadblock.

The Senate Appropriations Committee last week approved language -- two sentences buried in a lengthy report accompanying the Justice Department's spending bill -- stating that no money is provided for a tobacco lawsuit or expert witnesses to testify in such a case. The Justice Department had sought $20 million in its budget to finance the suit.

Sen. Judd Gregg (R-N.H.), who chairs the subcommittee that oversees Justice Department spending, said the department "doesn't have the resources to undertake this lawsuit and shouldn't be" doing so. He added that the lawsuit is a "backdoor" effort to go after billions won by the states in settlements with the tobacco industry last year.

The proposed federal suit would seek to recover money spent to treat smoking-related illnesses through Medicare and other federal insurance programs.

Democratic Sens. Richard J. Durbin (Ill.) and Bob Graham (Fla.), both tobacco foes, said they would fight to eliminate the language. "I don't know . . . how this snuck into this report," Graham said. Durbin, a member of the Appropriations Committee, said the tobacco industry, which last year worked to kill a national tobacco bill, must still "think it owns a piece of this place."

Durbin plans to offer an amendment on the Senate floor to make it clear the Justice Department can bring the lawsuit "on behalf of taxpayers."

Graham derided Gregg's reasoning that the department could not afford to mount the lawsuit, noting that it was Gregg's subcommittee that denied the funding. "That sounds like the argument of a child who has shot his mother and father and asks for mercy because he is an orphan," Graham said.

Matthew Myers, of the Campaign for Tobacco-Free Kids, said blocking the proposed suit would "provide the tobacco industry with virtual government immunity."