He failed at running the RNC and has failed at being a senator:

U.S. Sen. Mel Martinez of Florida, who has struggled to boost his approval ratings because of close ties to President George W. Bush, announced Tuesday he will not seek a second term in 2010.

His seat was widely seen as vulnerable in two years, but Martinez, a Republican, rejected suggestions he faced difficult re-election prospects in a state won last month by Democrat Barack Obama.

Martinez doesn’t think he has an approval rating problem, although he is stuck at 42%. Maybe he is quitting to spend time with his failures?