Washington -- SARS, the mysterious new respiratory ailment that has terrified people around the globe, has extended its reach to the Capitol, where Senate Republicans are using the disease to press their case that vaccine manufacturers should be shielded from lawsuits.

Led by Senate Majority Leader Bill Frist, Republicans are trying to revive the long-stalled measure. On Tuesday, Frist linked his bill to severe acute respiratory syndrome, or SARS, warning that pharmaceutical companies will not produce vaccines against the disease unless they are protected against "frivolous suits" that could drive them out of business.

"If we need a vaccine for this potential global epidemic, are we prepared?" Frist asked during a press conference to publicize the bill. "The answer is no,

absolutely not."

But whether that argument will hold sway in the Senate is unclear. With the Committee on Health, Education, Labor and Pensions set to take up the legislation today, Republicans and Democrats negotiated over a controversial provision that would dismiss thousands of lawsuits filed by parents who contend a mercury-based vaccine preservative, thimerosal, caused autism in their children.

Democrats are pressing for language to permit the parents to seek compensation through a special government "vaccine court," even if their claims fall outside the six-year statute of limitations Frist has proposed.

"We're close," said Sen. Christopher J. Dodd, D-Conn., a central participant in the negotiations. Asked about the Republicans' SARS argument, Dodd shrugged. "We're talking about childhood vaccines. It's another issue," he said.

Sen. Tom Daschle, the Democratic leader, predicted Democrats would eventually back the vaccine bill. "It has been improved," he said, "and in spite of some misgivings, I think many of us would be inclined to support it."