A lifelong Democrat, in 2001 Michael Bloomberg found the party too packed with career politicians to give him any shot at becoming New York City mayor. He ran as a Republican instead, and won. He stayed put for the next few years, raising money for the GOP's 2004 convention in New York City and contributing to the campaigns of President George W. Bush and other Republican candidates. In 2007, however in what was widely viewed as a prelude to a presidential run Bloomberg bolted, dismissing the political-party system as a "swamp of dysfunction" and registering as an independent. But old habits die hard: for the 2009 mayoral election, Bloomberg is running on both the independent and Republican tickets.
The Crist Switch: Top 10 Political Defections
Florida Governor Charlie Crist announced April 29 that he will leave the Republican Primary and run for the U.S. Senate as an independent. He is not the first to change sides. Over the years, scores of politicians have danced from one side of the aisle to the other. TIME rounds up the top 10 political defections in U.S. history