House and Senate negotiators moved closer to inking a final 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 time ran out as the Senate left Washington on Thursday to do last-minute campaigning before the Nov. 5 election. House lawmakers departed a day earlier.

Lawmakers worked until the final minutes, but were unable to get the final House and Senate leadership signatures on a compromise negotiators said would have the government cover 90 percent of all terror losses after insurance companies pay an initial amount of $10 billion.

"I regret we were unable to get that done, but I believe that before the final gavel comes down on this session, whenever that is, the Congress of the United States will have a chance to express its approval for this effort,'' said Sen. Christopher Dodd, D-Conn., one of the chief negotiators.

Lawmakers also worked on other national security items before leaving, including a port security bill, which would give the Coast Guard additional powers and require background checks of some port employees and new tracking systems for commercial ships.

Since the Sept. 11 terror attacks, concerns have been raised about possible attacks on ships containing highly flammable liquids or on fuel farms near ports, as well as the possibility of a nuclear weapon or other device hidden inside a container ship.

The House and Senate had both passed a port security bill and worked out their main differences but couldn't agree on how to come up with the $1.2 billion to pay for it.

Lawmakers also found out Thursday that it may be several years before border checkpoints will have the equipment needed to detect nuclear material being smuggled into the country. Despite spending more than $11.2 million to install portal radiation monitors in Russia, only one U.S. border point has them.

"Our ports and borders are not significantly more secure against nuclear smuggling than before the (Sept. 11) attacks,'' said Rep. Billy Tauzin, R-La., chairman of the full Energy and Commerce committee.

Portal monitors are designed to scan individuals and vehicles for nuclear material as they pass through checkpoints on the nation's borders or at other entry points, such as airports.

U.S. Customs Commissioner Robert Bonner said the agency has bought 172 portal radiation monitors, with 40 of them expected to arrive soon. Customs plans to have 400 of the devices within a year.

House and Senate negotiators also made one final push to get something done on terror insurance.

The legislation is supposed to protect the insurance industry from calamitous losses in the event of another 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.

House and Senate negotiators agreed to 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, a Democratic Senate source said, speaking on condition of anonymity.

But it soon became apparent that lawmakers still had some issues to work out. 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.