The U.S. Pension Benefit Guaranty Corp. soon will assume responsibility for a pension plan covering about 11,000 workers from auto supplier Metaldyne Corp., a person familiar with the matter said Thursday.

Metaldyne, struggling amid the slowdown in the auto sector, filed for bankruptcy protection in May and is attempting to reorganize itself. Exact details on the arrangement between the pension insurer and Metaldyne still aren't known. The pension plan in question covers active and former workers at the company.

A company official wasn't immediately available for comment.

The PBGC has expressed concern that Metaldyne's asset sales could lead to the termination of its pension plans. In papers filed Wednesday with the U.S. Bankruptcy Court in Manhattan, the agency objected to the proposed sale of the company's chassis business because it doesn't include the assumption of pension obligations.

PBGC attorneys said if that sale and other proposed transactions proceed without the assumption of the pensions, the plan will "likely terminate." Metaldyne also is seeking to sell its powertrain unit.

In court documents, the PBGC estimated that Metaldyne's pension plan is underfunded by more than $150 million.

Based in Plymouth, Mich., Metaldyne is a manufacturer of powertrain and chassis components for the automotive industry.

PBGC's expected assumption of Metaldyne's pension plan follows a rash of auto-supplier retirement plans that have been seized by the agency.

Most recently, PBGC agreed to take on $6.2 billion in pension liabilities from auto supplier Delphi Corp. (DPHIQ), which is in bankruptcy protection. That pension rescue is the PBGC's second-largest ever, ranked by dollars, after that of UAL Corp.'s (UAUA) United Airlines in 2005, which totaled $7.5 billion.

In an attempt to mitigate how many pensions PBGC is required to take over, the agency launched a campaign earlier this year encouraging companies to come to it and negotiate changes to strained pension plans before plant closures or plan terminations.

This effort led to the $55 million deal PBGC brokered with Visteon Corp. (VSTN). The former Ford Motor Co. (F) parts unit agreed to accelerate a $10.5 million cash contribution to the plan, provide a $15 million letter of credit, and have Visteon and its affiliates be responsible for up to $30 million in contingent pension obligations.

Still, the agency's $33.5 billion deficit remains a concern for lawmakers, as the economic recession lingers and more businesses reorganize or close in response to the downturn.

-By Darrell A. Hughes, Dow Jones Newswires; 202-862-6684; darrell.hughes@dowjones.com

(Eric Morath and Jeff Bennett contributed to this report.)