GM: ResCap May Ram Auto Finance

Meanwhile, speculation is rampant on Wall Street that ResCap could be headed for bankruptcy and default rates could begin to spike in GMAC's auto finance business as the housing debacle takes its toll on consumer spending.

Henderson's remarks fed those fears, and he also said he expects U.S. vehicle sales to be around 15.7 million vehicles in 2008, down 300,000 from GM's prior projections for the industry. Henderson said there's "more downside than upside" in his forecast, and he said a recession could lead to vehicle sales closer to 15 million.

In light of the slowdown, GM has plans to further thin the ranks of its blue-collar workers, Henderson said. The company will unveil the details of its attrition plan in the months ahead.

As for GMAC, the finance company recently reported that its mortgage unit's net worth had dropped to $6.2 billion at the end of its third quarter from $8.4 billion a year earlier. Last week, GMAC announced a $750 million bond tender offer designed to boost ResCap's fourth-quarter earnings and keep its net worth above the $5.4 billion level.

If ResCap's net worth falls below that level by the end of the year, it could violate covenants on portions of its unsecured credit lines, potentially making it a candidate for bankruptcy. GMAC also said its management team will recommend "as necessary" another capital contribution to ResCap to ensure the lender is in compliance with the covenants.