The Senate yesterday overwhelmingly approved a bill to strengthen the nation's private pension system by requiring employers to pay higher premiums to the government's pension insurance agency and toughening rules for keeping plans adequately funded.

The measure, approved 97 to 2, also included a provision that would give Delta and other financially troubled airlines far more time than other companies to fully fund their pension plans. Bush administration officials have warned that such a timetable could greatly increase the cost to the pension insurance agency if the airlines ultimately fail, and yesterday the White House threatened a veto if that provision remains.

The House has completed committee action on a pension bill that lacks the special relief for airlines. Chairman John A. Boehner (R-Ohio) of the House Education and the Workforce Committee said yesterday that he expects a vote on the bill after Thanksgiving.

The Senate action came the day after the Pension Benefit Guaranty Corp. reported that the liabilities it has assumed to pay the pensions promised by failed companies remain more than $22 billion greater than its assets. The agency's executive director said the agency will run out of money if nothing is done.

An analysis last month by the PBGC concluded that neither the House nor the Senate bill strengthens the agency as much as would the administration's original proposals early this year. However, the PBGC prefers the House measure to the Senate's.

Strengthening the PBGC, which insures the pensions of about 44 million workers and retirees, isn't the only consideration.

Lawmakers have been in a difficult position as the changing economy and flat stock market have weakened many employers, especially airlines, steelmakers and companies in the automobile industry, making it more difficult to fund traditional pension plans.

Bankruptcies such as those of Bethlehem Steel and United Airlines have plunged the PBGC into the red, but some healthy employers warn that if the rules are tightened too much they will freeze or terminate their pension plans.

If the traditional system continues to shrink, as if has for the past two decades, more workers will be forced to depend on savings and 401(k)-type retirement plans that some experts fear won't be enough.

"It's a crisis. We see it with our airline workers. We see it with workers in manufacturing industries," said Sen. Edward M. Kennedy (D-Mass.).

Congress is also under pressure because a temporary technical measure passed two years ago to ease funding requirements expires at year-end. If that happens, the formula by which employers calculate their pension liabilities will change in a way that will make those liabilities much larger.

The Senate-passed bill would also require employers other than airlines to fully fund their pensions within seven years. The airlines would get 20 years.

Companies whose credit ratings are low would have to make additional payments to their plans. The PBGC has found that poor credit ratings are a good predictor of plans that will fail, but critics say requirements should be based on the condition of the pension fund, not that of the employer.

Other provisions of the bill include rules that would:

* Raise premiums paid to the PBGC to $30 per participant per year, from the current $19.

* Make it easier for companies to put money into the plans when times are good.

* Clarify that in the future cash-balance and other "hybrid" pension plans will not be regarded as violating federal age-discrimination laws.

* Require increased disclosure to workers of the financial status of their plans.