A group of private investors led by LBO giant Kohlberg Kravis Roberts & Co. (KKR) has offered to pay roughly $13 billion for GMAC, which is General Motors Corporation’s financing arm, reports the Wall Street Journal.

The non-binding bid allows the KKR consortium to back out of the deal. According to the Journal report, the non-binding nature of the bid is one of several finer details that have chilled GM’s reception to the offer. That would bode well for a rival bidder led by Cerberus Capital Management, which many have deemed the leading bid in recent weeks. Or it could persuade GM to seek out other interested parties outside of the KKR and Cerberus-led bidders.

GMAC posted net income of $2.22 billion in 2004, slightly below 2004 net income of $2.23 billion. Revenues increased year over year from $15.05 billion $15.83 billion, however.