A total of 33 Senate seats were up for grabs in the 2006 election. Of those, 18 were Democrat-held (including 1 Independent in Vt.) and 15 were Republican-held. Four of the races didn't include an incumbent. A strong showing on Election Day swung control of the Senate to the Democrats (49 Dem. Senators + 2 Independents who'll caucus with Dems.)

<<< Click on the states for an overview of the races.

Credits:
CBS/The Cook Political Report/The National Journal