Hillary Clinton shakes voters' hands on the eve of her re-election to the U.S. Senate in November 2006.

Clinton's re-election was fairly easy, with relatively high support from her New York constituents. She faced a much tougher battle when she first sought the Senate seat in 2000. Her opponent in that race initially was New York City Mayor (and future presidential candidate) Rudy Giuliani, but Giuliani dropped out of the race when he was diagnosed with prostate cancer. (© AP Images)

In the Senate, Clinton serves on the powerful Senate Armed Services Committee with Arizona Senator John McCain.

(© AP Images)