A House vote on a lengthy extension of the federal terrorism insurance backstop is likely to be delayed beyond next week, in part because of concerns about compliance with pay-as-you-go budget rules.

Barney Frank, chairman of the House Financial Services Committee, said Thursday that a Congressional Budget Office (CBO) estimate of the potential cost of a bill (HR 2761) to extend the Terrorism Risk Insurance Act (TRIA) could prevent House lawmakers from considering the measure early next week as expected.

The House Rules Committee had been set to consider a rule for floor debate on the measure Friday, but that meeting was postponed Thursday afternoon and not immediately rescheduled.

Supporters of the legislation, which would extend and expand the TRIA law passed in 2002 (PL 107-297), had hoped to tie consideration of it to the six-year anniversary of the Sept. 11 terrorist attacks.

Created in response to heavy losses that property and casualty insurers suffered after the terrorist attacks, the program obligates the federal government to help pay for the costs of a large-scale attack once losses meet a certain threshold.

“There’s a question of PAYGO with TRIA. And that’s being debated,” said Frank, D-Mass. “My own view is, that’s kind of puzzling because TRIA doesn’t spend a penny unless there is an attack. We’re trying to work out the PAYGO issue.”

Further complicating consideration of the bill is the funeral of Rep. Paul E. Gillmor, R-Ohio, who died Sept. 5. Majority Leader Steny H. Hoyer, D-Md., said votes were unlikely on Sept. 11 so that members would have time to attend Gillmor’s funeral in Columbus, Ohio.

Democratic aides said the delay would most likely push a House floor vote on a TRIA extension to the week of Sept. 17.

The delay is related to Democrats’ pledge to operate under pay-as-you-go budget rules, which require any new mandatory spending or tax cuts to be fully offset.

Although House leaders could waive the rules, doing so could open them up to GOP accusations of selective rules enforcement.

Still, uncertainty about the precise costs of the measure might provide Democrats with the necessary political cover to avoid wrangling over offsets.

In a report released Thursday, CBO estimated that the 15-year extension of the program would increase the budget deficit by $3.5 billion over the next five years and $8.4 billion over the next decade. But supporters of the bill could have grounds for challenging the estimates, as CBO acknowledges that the costs of the legislation are hard to predict.

“There is no reliable way to predict how much insured damage terrorists might cause in any specific year,” the report said. Instead, CBO’s estimates are based on a weighted average of cost scenarios that estimate the expected value of payments from the program. CBO also noted that “there is a very limited history of terrorist attacks in the United States.”

The bill is supported by larger insurers. But it has been opposed in part by smaller insurers and by many GOP lawmakers who have argued that a 15-year extension exposes taxpayers to too much risk.

Supporters are working to salvage the bill.

“It seems that the CBO has substituted itself for the FBI: They know when the attacks are coming,” quipped one lobbyist.

A two-year extension (PL 109-144) of the program is set to expire Dec. 31. Lawmakers in both chambers have expressed a desire to extend it before the end of the year.

Michael R. Crittenden contributed to this story.