Obama, McCain Begin Running-Mate Searches

Sen. Barack Obama campaigns at the B'nai Torah Congregation in Boca Raton, Fla. Obama emphasized that his nomination battle with Sen. Hillary Rodham Clinton is not over but said, "Two weeks from now, we will know who the Democratic nominee is going to be." (By Chris Carlson -- Associated Press)

He added: "By the way, that does not exclude Republicans, either. The best person for the job is the person I would want."

Among others, Obama is expected to look at seasoned Democratic statesmen such as Sen. Joseph R. Biden Jr. (Del.) and former senator Sam Nunn (Ga.). Biden, who has twice sought the presidency, including a 2008 bid, comes from a working-class Irish Catholic background -- a demographic Obama has struggled with in the primaries. Sen. James Webb (Va.) is another potential prospect, a decorated Marine and former Republican with strong working-class support in his GOP-leaning state.

Some Obama insiders think he will consider a number of female candidates, including Kansas Gov. Kathleen Sebelius, Arizona Gov. Janet Napolitano and Sen. Claire McCaskill (Mo.). All three endorsed Obama early in his campaign.

In the interest of party unity, Obama could turn to a Clinton supporter from a swing state, such as Sen. Evan Bayh (Ind.), Pennsylvania Gov. Ed Rendell or Ohio Gov. Ted Strickland. Republicans who could land on his radar screen include Sen. Chuck Hagel (Neb.) and New York Mayor Michael R. Bloomberg, now a political independent.

McCain has said consistently that he wants a running mate who shares his beliefs and would be prepared to take over the presidency. But his team is also taking political calculations into consideration, including geography, age and expertise on domestic issues. One Republican pointed to Crist as a potential boost for McCain in Florida.

Eilperin was traveling with McCain in California. Staff writer Anne E. Kornblut in Washington contributed to this report.