If President Bush's pension-funding proposals were enacted, companies that operate traditional pensions would have to put about $430 billion more into their plans collectively than is required under present law, according to figures from the government's pension insurance agency.

The figures, disclosed by Rep. George Miller (D-Calif.), who obtained them from the Pension Benefit Guaranty Corp. under the Freedom of Information Act, also show that Bush's proposal would balance the agency's books by 2016. The PBGC has swung sharply into deficit in recent years, and administration officials and others have expressed concern about a possible savings-and-loan-style government bailout.

Miller said the Bush proposal's requirements would mean a 75 percent increase in the amount of money employers would have to pay into their pension funds over the next six years -- taking the total for those years to more than $1 trillion -- and in certain years would more than double the required payments.

The additional contributions would come on top of sharply higher PBGC insurance premiums that the administration has proposed to assess employers. If enacted as the president proposed, those premiums could add as much as $18 billion to employers' costs over five years.

But there is also concern that tightening the rules too much will cause more companies to abandon their pension plans, which thousands already have done over the past two decades. That shift has left millions of U.S. workers with Social Security and savings they have been able to accumulate through 401(k) and similar arrangements to see themselves through retirement.

"It's a stunning increase in the contributions" required of employers, Miller, the ranking minority member on the House Committee on Education and the Workforce, said yesterday. "The question is, do these increases cause companies to want to terminate or get rid of in whatever fashion" their traditional pensions.

Both the House workforce panel and the Senate Finance Committee have approved pension proposals; the Senate's proposal is somewhat closer to Bush's than the House's. The PBGC has not yet worked out figures for those measures.

Lawmakers don't have a clear picture of the true impact of the proposed changes, Miller said. "We are rushing forward with this legislation . . . without any information."

Workforce Committee Chairman John A. Boehner (R-Ohio) called that argument "simply a smoke screen."

"For months, Democrats had been clamoring for legislative action, and yet they've refused to propose any comprehensive solution," Boehner said.

Traditional pensions, which typically pay a benefit related to a worker's pay and years of service, have been hit hard in the past five years by poor investment performance and low interest rates. Total underfunding in the weakest plans -- those with liabilities that exceed assets by $50 million or more -- reached $353.73 billion last year, according to the PBGC. The agency, after taking over plans such as those of Bethlehem Steel and United Airlines, now faces a deficit of its own -- $23.5 billion as of last fall.

Employer groups said demanding so much more money from employers might be counterproductive.

"I think the PBGC has acknowledged what we have warned all along: that a draconian administration proposal could make the termination of underfunded plans a self-fulfilling prophecy, and drive thousands of well-funded plans out of the system," said James A. Klein of the American Benefits Council, an employer group.

"It's a stunning increase in the contributions" from employers, says Rep. George Miller (D-Calif.).