Washington ? Hoping to reverse the deterioration of pension plans covering 44 million Americans, the Senate voted Wednesday to force companies to make up underfunding estimated at $450 billion and live up to promises made to employees.

The action came a day after the federal agency that insures such plans reported massive liabilities and predicted a troubled future.

The Senate legislation, passed 97-2, takes on the daunting task of compelling companies with defined-benefit plans to live up to their funding obligations – without driving those companies into abandoning the plans and further eroding the retirement benefits of millions of people.

The White House, in a statement, said it supported passage of the Senate bill but opposed some provisions, including extended relief for the airline industry. It warned that the president would be advised to veto any bill that resulted in weakening pension funding requirements.

The House could take up a companion bill in December.

The vote came a day after the Pension Benefit Guaranty Corp., which insures defined-benefit plans of 44 million people and takes over the plans of bankrupt companies, reported a deficit of $22.8 billion at the end of the 2005 fiscal year on Sept. 30.

The PBGC said it assumed responsibility for the pension benefits of an additional 235,000 workers and retirees in 2005, bringing the total to 1.3 million, and paid benefits of $3.7 billion, up from $3 billion in 2004.

Premiums per participant, paid by companies, would increase from $19 to $30 a year under the Senate bill.