UPDATE 1-S&P may cut GMAC, ResCap may go to junk status

(Updates with GMAC rating action)

NEW YORK, Oct 17 (Reuters) - Standard & Poor's on Wednesday said it may cut its ratings on GMAC LLC deeper into junk status, and that its mortgage lending unit Residential Capital could also be downgraded into speculative-grade territory.

ResCap had historically been a significant contributor to GMAC's performance, S&P said in a statement, saying the possibility of a cut was based on the mortgage lender's worsening prospects.

ResCap said on Wednesday it will eliminate 3,000 jobs, or 25 percent of its work force, to cope with the U.S. housing downturn.

S&P said it may cut ResCap's counterparty and senior unsecured ratings, which are now "BBB-minus," the lowest investment grade. Counterparty credit ratings reflect how well a company can meet its financial obligations with customers, trading partners or other parties.

S&P said it may also cut GMAC's counterparty and senior unsecured ratings, now "BB-plus," the highest junk level. (Additional reporting by Jonathan Stempel)