General Motors Corp.'s plan to cut 30,000 jobs and close a dozen plants shows how tough things have gotten for the company that long dominated the U.S. car market.

GM's woes are ominous for its employees and for those of other businesses, such as auto-parts suppliers, whose fortunes rise and fall with the manufacturing giant. But they also raise the risk facing U.S. taxpayers from the country's ailing pension system. And they increase the urgency for Congress to reform the system.

U.S. employers offering traditional defined-benefit pension plans have, as a group, fallen $450 billion behind in funding their obligations. Longer life spans and several years of low investment returns have hurt the financial health of pension plans. But so have lax federal rules that have let companies promise benefits they can't afford, and skimp on or even skip payments to their plans.

The federal agency that insures pensions for more than 44 million Americans, the Pension Benefit Guaranty Corp., reported this month that it has a $23.1 billion deficit. Although that total improved slightly from last year, the agency still is facing a long-term funding gap that could grow too large to close without a huge, savings-and-loan type bailout from taxpayers.

The pension agency was designed to be financed with company premiums. But premiums haven't been raised in more than a decade. And as airlines and other companies have declared bankruptcy and dumped their underfunded pension plans on the agency, its deficit has ballooned.

Such a move from GM could be the mother of all pension defaults. The pension agency has estimated that the automaker's retirement promises are underfunded by $31 billion.

Recently, the Senate overwhelmingly passed a pension-reform proposal. It has some positive features: an increase in premiums for the pension agency; better disclosure about the financial health of pension plans; and measures to deter companies from declaring bankruptcy to dump their plans.

But because of loopholes and exceptions in funding rules, the Senate proposal actually would, overall, reduce required company contributions to their plans, according to the pension agency. That could lead ultimately to more failed plans and a bigger bailout for taxpayers.

The House is still working on its own version of pension reform. Members need to come up with a better proposal: one that would provide a more secure future for pensioners while making a taxpayer bailout of the system less likely.

Ideally, GM's cutbacks will help the company recover. GM officials insist they have no plans to terminate their pension plan. Regardless, Congress needs to agree on steps to shore up the pension system, so taxpayers don't end up holding the bag.