GMAC LLC has "limited if any access to funding" for its mortgage and auto lending units, Alvaro G. de Molina, its chief executive officer, wrote in an e-mail to employees.

The Detroit company may trim auto lending in some international markets, Mr. de Molina wrote Tuesday in the e-mail, and it is considering "strategic initiatives" for its insurance businesses.

"We've pursued a 'self-help' approach that on some days is akin to hand-to-hand combat," the e-mail said. The lender's Residential Capital LLC is "perhaps the most challenged operation."

Gina Proia, a spokeswoman for GMAC, said it does not discuss employee communications.

Plummeting auto sales and record foreclosures have resulted in $5.4 billion of losses at GMAC over the past year and have led credit agencies to downgrade its debt to junk status.

"It's very difficult for a finance unit to exist very long at less than investment grade," said Thomas Atteberry, who helps manage $3.5 billion of fixed-income assets at First Pacific Advisors LLC in Los Angeles. "The cost of capital is just a killer."

Mr. de Molina said that Cerberus Capital Management LLC, which bought 51% of GMAC from General Motors Corp. in 2006, "may evaluate new and creative solutions to the problems" resulting from the current environment.

"There has been no decision to change GMAC's ownership structure at this time," he added.

ResCap, GMAC's mortgage lending unit, has reported losses for seven straight quarters as a result of the worst housing crisis since the Great Depression.

Thomas Marano, ResCap's CEO, is working on a "three-prong" approach to revive the business, including "revenue-generating strategies for the current marketplace" and improving communication among employees, Mr. de Molina said.

GMAC, which generated 43% of GM's auto loans in the second quarter, is restricting auto lending to buyers with credit scores of at least 700; about 58% of U.S. consumers have a score that high.

The announcement added to the global credit squeeze that threatens to choke economic growth as companies and consumers find it harder and more expensive to borrow.

Also this week, GMAC raised the rate it charges auto dealers for making loans that are not part of special incentive programs by 75 basis points. It also said most loans will be limited to 60 months.

Last year GMAC derived 42% of its revenue from automotive finance, which provided 29% a year earlier. The share of revenue from insurance rose to 42%, from 38% in the previous year.

Amber Gowen, a spokeswoman for Chrysler Financial, the finance arm of the Cerberus-owned Chrysler LLC, said it has not changed its standards for auto lending.

In a report issued Wednesday, Standard & Poor's Corp. said that the Federal Reserve Board's plan to bring liquidity back to the commercial paper markets may help auto lending units.

However, the lenders' access to capital is likely to remain limited into next year, Ernest Napier, a credit analyst at S&P, wrote in the report.

"We'll need to keep our eyes on the ability of these auto finance companies to find new funding sources and capabilities, because we really don't know when the asset-backed securities market will stabilize for them," Mr. Napier wrote.

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