6. Chris Dodd

Sen. Dodd (D-Conn.) is widely regarded as one of the most vulnerable incumbent senators heading into the 2010 elections. Many have been looking to Dodd, the chairman of the Banking, Housing and Urban Affairs Committee, for economic solutions. But his role in the Senate’s economic debate this year was clouded by revelations concerning his ties to the Countrywide mortgage controversy. That scandal and other factors have pushed Dodd’s approval ratings deep into the red. In addition, some voters still feel burned by Dodd’s decision to move his family to Iowa during his failed bid for president in 2008. Discussion about a Dodd resignation or retirement continues despite the senator’s protestations.

Next — 5. John Edwards