Claire McCaskill (D)

(Charlie Riedel - AP)

State Auditor Claire McCaskill narrowly lost a 2004 gubernatorial bid after defeating her party's sitting governor in the primary. She endured another cliffhanger this fall in her successful challenge of Sen. James M. Talent (R), who repeatedly accused her of being a liberal in moderate's clothing.

McCaskill, 53, is a fourth-generation Missourian, a high school homecoming queen and the daughter of Columbia's first female city council member. McCaskill was a state legislator in the 1980s and became the first female Jackson County prosecutor in 1993. She gained a reputation as a tough government watchdog in her role as auditor, starting in 1999.

McCaskill made a point of reaching out to rural Missouri voters, who traditionally have voted Republican, and also appeared to benefit from the high Democratic turnout inspired by two state initiatives that she supported. One called for no state restrictions on embryonic stem cell research more strict than those imposed by Congress, and another mandated an increase in the state's minimum wage to $6.50 an hour. Both passed.