WASHINGTON » The federal agency that insures pensions for more than 40 million Americans ran the widest deficit in its 38-year history last year.

The Pension Benefit Guaranty Corp. said Friday that its deficit grew to $34 billion for the budget year that ended Sept. 30. That compares with a $26 billion shortfall in the previous year.

Pension obligations grew by $12 billion to $119 billion. Assets used to cover those obligations increased by only $4 billion to $85 billion.

The agency has now run deficits for 10 years, the gap widening because of the weak economy.

If the trend continues, the agency could struggle to pay benefits.

Agency Director Josh Gotbaum, the Hawaiian Airlines trustee during the company’s bankruptcy from 2003-2005, said continued deficits "will ultimately threaten" the PBGC’s ability to pay pension benefits to retired workers.

"There’s no imminent threat that we’re going to stop cutting checks," Gotbaum said. However, he said, Congress must act "long before 10 years from now" to increase the insurance premiums that companies pay to the agency.