Obama close to choosing his running mate

Biden, the chairman of the Senate Foreign Relations Committee, falls into the category of helping Obama on foreign policy, while Kaine is a relative newcomer to national politics and would reinforce the notion of change. Both Kaine and Bayh would help Obama in a state that Democrats are trying to put in play.

For all the attention to Obama's deliberations, it is by no means assured that his choice will make a big difference in the outcome of the campaign.

"It's not that important," said Matt Bennett, the co-director of Third Way, a moderate Democratic advocacy group that has not taken a position in the race.

"Vice presidential candidates can make a marginal difference," Bennett said, "but they rarely matter in terms of winning a state or region — as Mike Dukakis and John Kerry found out. And a weak candidate doesn't really drag the ticket into the drink — as George H.W. Bush found out."

Still, the choice will provide Obama a chance to reclaim the public spotlight after what many Democrats say has been an unsteady patch, setting the tone as he heads into his convention in Denver next week.

The staff members of the vice presidential team reported to duty in Chicago two weeks ago, not knowing who they would ultimately be working for.