Congressional negotiators say they reached a tentative agreement on a $100 billion terrorism insurance package that lawmakers hope will stimulate the economy and help cover the cost of insurance against future terrorist attacks.

But final passage of the legislation is still not assured. It has not been formally approved by a Senate-House conference where some members continue to have reservations about parts of the package. And then it must still be approved by both the full Senate and House, which has recessed until after the Nov. 5 election.

Some GOP lawmakers in the House wanted a provision included to limit lawsuits against companies struck by terrorists. There also continues to be disagreement over whether insurance companies must pay back the government for any economic bailouts prompted by an attack.

Several House-Senate compromises -- including a bankruptcy reform bill and an agreement on forming a commission to investigate the government's failure to predict the Sept. 11 attacks -- have never made it through Congress, although lawmakers announced settlements.

On the terrorism insurance measure "we believe we've got an agreement," Sen. Christopher Dodd, D-Conn., one of the chief Senate negotiators, said Thursday. "We obviously depend upon other people signing on it to confirm it. I think that's going to happen."

House Financial Services Committee Chairman Michael Oxley, R-Ohio, also was optimistic.

"As in any conference agreement, everyone must compromise and that is what we have done here. The U.S. economy must come before our individual preferences in the legislation, and today we have put the nation's workers first," said Oxley.

A Senate Democratic source, speaking on conditions of anonymity, said the agreement was on a three-year, $100 billion package that would have the government cover 90 percent of all terror losses after insurance companies pay an initial amount of $10 billion.

The GOP-controlled House and the Democrat-controlled Senate have passed different versions of legislation, which would protect the insurance industry from calamitous losses in the event of another terrorist attack by requiring the government to pick up some of the losses.

Many insurers, who faced record payouts after Sept. 11, limited or dropped coverage for casualty and property losses due to terrorism. But with most lenders requiring insurance to finance real estate, plant expansion and other construction projects, industry representatives have warned of damage to the economy.

Lawmakers said they would release details of the agreement later. While there was agreement on the broad outline of the legislation, some parts of the agreement remained in flux.

For example, the Senate source, speaking on condition of anonymity, said the treasury secretary would have discretion to require insurance companies to repay the government for its help, but that the legislation does not require such a payback.

However, a Republican House source, also speaking on condition of anonymity, said insurance companies would be required to pay the government back for the first $15 billion of an economic bailout. Beyond that, the treasury secretary must collect the money but has discretion as to when and how, the GOP source said.

Oxley, in a statement released Thursday, said a mandatory payback "was a must-have item for the House."

The bill also does not shield companies from punitive damage awards in the civil lawsuits that arise after terrorist attacks.

Administration officials said the White House sought to shield companies from those lawsuits -- a hot button issue for both Democrats and Republicans-- but Senate Democrats balked at the idea and it was not included in the final agreement .

Republicans in Congress accused Democrats of trying to protect trial lawyers, while Democrats charged Republicans were looking out for businesses that are major GOP donors.

A spokesman for House Judiciary Chairman James Sensenbrenner, R-Wis. -- a compromise negotiator who advocated capping punitive damages -- said that Sensenbrenner had not yet signed off on the legislation.

President Bush and the GOP have pushed vigorously for the legislation, saying as much as $15 billion in construction and real estate transactions and 300,000 jobs are on hold because Congress has not acted on terrorism insurance legislation.

"We are very pleased with the progress that has been made in the last couple of days toward reaching an agreement," said White House spokeswoman Claire Buchan. "The parties are very close and the main elements of a deal are falling into place. We do not have a deal, but we are very encouraged."