GMAC announced Monday that Al de Molina has resigned as its chief executive and from the board.
Michael A. Carpenter, a director, succeeded de Molina as CEO of the troubled auto and mortgage lender.
GMAC, which is 35% owned by the government, also said the board had asked the Treasury Department to postpone making a decision on the company's request for a third, $5.6 billion investment.
Carpenter and the rest of GMAC's management team want to "assess the current situation" to advise the board and Treasury "regarding the appropriate amount and form of such funding."
De Molina, a former chief financial officer of Bank of America, joined GMAC in 2007 as chief operating officer.
Carpenter, 62, joined GMAC's board in May. He spent 11 years in various roles at Citigroup.