In 2000, Kyl cruised to re-election when Democrats didn't even both putting up a candidate. Kyl crushed two minor party candidates and an independent. Six years later, Kyl had a roughly 150,000-vote edge over Pederson, out of roughly 1.5 million votes cast.
Pederson, a shopping center developer, sunk $10 million of his own money into the race.
Republicans mentioned as possible candidates for the seat include U.S. Rep. Jeff Flake, former U.S. Rep. John Shadegg and former state Treasurer Dean Martin. Besides Giffords and Pederson, another Democrat whose names figure in speculation is former Gov. Janet Napolitano, currently the U.S. Homeland Security secretary.
"The strongest (Democratic) candidate would be Napolitano," said Arizona State University political science professor Patrick Kenney, citing her three statewide election wins and probable strong fundraising ability.
But Kenney also said Napolitano would face attacks from Republicans for having quit in the middle of her second term as governor to go to Washington at the beginning of a state budget crisis.