The airline industry, facing what it claims could be catastrophic losses, is mounting a major campaign to get Congress to shield it from potentially billions of dollars of liability stemming from Tuesday's hijackings and terrorist attacks.

At the same time, Republican and Democratic leaders of the House have agreed on a $15 billion package of grants, loans and tax waivers to bail out airlines from a financial disaster in the wake of the terrorist strikes.

The industry and its supporters say the airlines, including United and American, which each lost two planes in the disaster, will almost surely be forced into bankruptcy if they have to pay huge liability claims to the survivors of the more than 5,000 people believed to have been killed in the planes and at the World Trade Center and the Pentagon.

All airlines also face a loss of revenue from the temporary halt to air traffic and the financial burden of adding more security for their flights. Passenger traffic also is likely to drop because of fears of more attacks and the inconveniences caused by new security measures.

"There's a pretty strong [lobbying] effort going on," said Andy Davis, a spokesman for Sen. Ernest "Fritz" Hollings (D-S.C.), chairman of the Senate Commerce Committee, which has jurisdiction over aviation issues. Davis said Hollings believed it was premature for Congress to act on the issue.

Sen. John McCain (Ariz.), the Commerce Committee's top-ranking Republican, is sympathetic to granting some liability protection to the airlines for the hijackings but is opposed to granting them blanket immunity for lawsuits arising out of the incidents, an aide said.

One congressman, who declined to be identified, said House Minority Leader Richard Gephardt (D-Mo.) was a key backer of the liability protection movement for the airlines. However, a Gephardt spokesman said the congressman had not yet developed a position on the proposal.

Several congressional sources identified Sen. Christopher Bond (R-Mo.) as another vigorous promoter of the idea, although his spokesman was not available Friday.

The constituencies of both men include St. Louis, a major operations hub for TWA, which was recently acquired by American Airlines.

United spokeswoman Susan Leyva said forcing the nation's two largest airlines to pay the price for the destruction caused Tuesday could irreparably harm not only them but other airlines as well.

"We are unable to ignore the fact that if United and American were compelled to shoulder a large portion of the financial burden of this brutal and horrible attack, it would have a debilitating effect on the jobs and the employees of our companies as well as America's air transportation system," Leyva said.

"This tragedy caused by terrorist acts is not an ordinary aircraft accident. We think this event requires an appropriate response by the federal government and the entire nation."

A spokeswoman for American said the airline shared the sentiments expressed by Leyva.

Meanwhile, House Speaker Dennis Hastert (R-Ill.) and Gephardt have agreed to back a financial assistance package for the airline industry that would provide $2.5 billion in grants and $12.5 billion in loan guarantees and waivers of fuel tax payments.

The two leaders sought unanimous consent from House members to bypass normal procedures and pass the aid package quickly. They argued that it was important to shore up confidence in the airline industry before the stock market reopened on Monday.

"The airlines need the reassurance in the short term," said John Feehery, a spokesman for Hastert. "This is to send a message to the markets that the airlines are stable."

The Business Travel Coalition, which represents large corporations that spend heavily on travel, urged Congress to move rapidly to provide some liability protection for the airlines. It cited concerns that fears of large lawsuits could provoke a creditors' run against the airlines.

"Congress must act decisively in defining United's and American's liability as a result of this act of war," said Kevin Mitchell, chairman of the organization. "Without lines of credit, shareholder confidence and traveler bookings, United and American could become the next Pan Am, and in short order. The country needs to support both its low-fare and major network carriers through this national crisis. Hundreds of thousands of jobs are at risk, as are the communities and businesses that depend on the airline industry."

Even the professional organization representing attorneys who sue companies like airlines for damage claims has urged its members to show restraint--at least for now. The Association of Trial Lawyers of America issued a statement calling on its members to temporarily hold off on filing lawsuits against the carriers involved in the attacks.

"For the first time in our history, the Association of Trial Lawyers of America, in this time of national crisis, urges a moratorium on civil lawsuits that might arise out of these awful events," Leo V. Boyle, the group's president, said in a message to members.

"There are more urgent needs that must be served at this time," Boyle said, adding that the group is prepared to work with Congress and the White House "to help assure unqualified justice and prompt relief for the thousands of innocent victims and their families."

Tribune staff reporter John Schmeltzer contributed to this report.