Could the US Lose its Triple AAA Credit Rating?

'That's the issue raised by a S&P report on government-sponsored enterprises (GSEs) -- Fannie Mae (FNM), Freddie Mac (FRE) & Sallie Mae (SLM) The performance of government-sponsored enterprises like Fannie Mae and Freddie Mac could have a direct impact on the national economy and, more importantly, U.S. credit standing.'