NEW YORK - GMAC Financial Services said Monday that Alvaro de Molina has stepped down as CEO, a surprise departure that comes as the troubled auto lender remains in negotiations with the government over its third round of taxpayer aid.

A person familiar with the situation said De Molina was asked to step down by GMAC's board of directors. The person declined to be named because the reasons behind De Molina's exit have not been made public.

Treasury Department officials stressed that they had nothing to do with Molina's departure, calling the decision "100 percent GMAC's." That's in contrast to the Obama administration's ouster earlier this year of GM CEO Rick Wagoner, who was pressured to step down as a condition for taxpayer aid.

GMAC director Michael A. Carpenter will take over as CEO. In an interview, Carpenter affirmed that no government entity had any say in De Molina's departure.

"To the contrary, the board reached its own conclusions," Carpenter said. "As the board looked forward, it decided that it really wanted some more strategic skills. It wanted more turnaround skills, more operations skills. So that is, in short, the basis I believe for a change."

De Molina's resignation comes as the lender is negotiating with the Treasury Department over additional taxpayer aid. GMAC is instrumental to the operations of automakers General Motors Co. and Chrysler Group LLC, but its finances have been haunted by bad loans it made during the housing boom.

GMAC, which became a bank holding company late last year, has received $12.5 billion in taxpayer money and is 35 percent owned by the federal government. The FDIC also took the rare step earlier this year of allowing the junk-rated company to gain access to its debt-guarantee program, called the Temporary Liquidity Guarantee Program. It agreed to guarantee up to $7.4 billion in GMAC-issued debt in case the company defaulted on payment.

But results of the federal government's "stress tests" earlier this year demanded that GMAC raise an $11.5 billion capital cushion to help it weather further economic decline. Of 10 banks asked to raise additional cash, GMAC was the only one that failed to be able to raise the funds privately.

The Detroit lender has asked the government to postpone any decision on additional taxpayer aid until Carpenter and the company's management assess GMAC's situation and are able to advise Treasury on the amount needed.

Carpenter told The Associated Press that the company would need no more than $5.6 billion in aid.