Another Senate Republican is set to retire, Ohio Senator George Voinovich. His seat was going to be difficult to retain with incumbency advantage - now it is more depressing news for the GOP. Also announcing 2010 retirement are Mel Martinez (R-FL), Sam Brownback (R-KS), and Kit Bond (R-MO). Missouri, Florida, and Ohio are all swing states. What is interesting to me is that Voinovich, by announcing right now that he will retire, liberates himself from threats to his re-election. In otherwords, he becomes harder for his own party to control.