About one-third of the US Senate's 100 seats are up for grabs on November 6. With 23 of those 33 seats being defended by Democrats, rival Republicans see a realistic -- albeit slim -- chance of gaining four seats and seizing control of the chamber. Here are six races to watch on election day:
- Incumbent Scott Brown (R) vs Elizabeth Warren (D),
- Incumbent Claire McCaskill (D) vs Todd Akin (R),
- Incumbent Jon Tester (D) vs Denny Rehberg (R),
- Incumbent Sherrod Brown (D) vs Josh Mandel (R),
- George Allen (R) vs Tim Kaine (D),
- Tammy Baldwin (D) vs Tommy Thompson (R).