The Illinois senator has staffers in place to aid the No. 2 and his or her spouse, including more than a dozen seasoned operatives who have set up shop in a section of the campaign's Chicago headquarters. They are running through various logistical scenarios involved in taking over the relatively normal life of a person they do not know and thrusting them into the unrelenting glare of a presidential campaign.
Obama was believed to have narrowed his list to Virginia Gov. Tim Kaine, Delaware Sen. Joe Biden, Indiana Sen. Evan Bayh and Kansas Gov. Kathleen Sebelius. While it seemed increasingly unlikely that he would choose his vanquished rival, New York Sen. Hillary Rodham Clinton, some Democrats speculated Monday that he could pull a surprise and pick her.
CBSNews.com tracks the veepstakes buzz and ranks the top contenders.
Former South Dakota Sen. Tom Daschle, a close Obama adviser, said Monday he had given the campaign personal information needed to examine the background of potential vice presidential nominees but was confident he wouldn't be selected.
"I did give ... documents a long time ago, but these matters have been resolved for a long time now as far as I'm concerned," Daschle told The Associated Press in an interview.
Only Obama, his wife, Michelle, a handful of his most senior advisers and his two-member search committee know for certain who was on the initial list, who made the cuts, whose backgrounds were researched, whose names were floated to divert the media - and who Obama ultimately will choose.
He planned to campaign in Florida on Tuesday, and on Wednesday ride a bus through North Carolina and Virginia, where he was appearing with former Gov. Mark Warner, also mentioned as a possible contender for the No. 2 spot. After that, Obama's schedule is wide open, leaving the end of the week as a more likely time to make the announcement before the Democratic National Convention begins next Monday in Denver.
Campaign manager David Plouffe e-mailed supporters last week telling them they would receive first word of Obama's decision through a mass text message, but otherwise the team has revealed little about what to expect. Historically, presidential tickets then tour battleground states to maximize media exposure, and Obama is expected to do the same.
For his part, Republican rival is seriously considering naming his running mate between the end of the Democratic convention Aug. 28 and the Sept. 1 start of the GOP convention in hopes of stunting any uptick in polls for Obama. McCain has at least three large rallies planned in top battlegrounds - Ohio, Pennsylvania and Michigan - before the Republican gathering in St. Paul, Minn.
His top contenders are said to include Minnesota Gov. Tim Pawlenty and former Massachusetts Gov. Mitt Romney. Less traditional choices include former Pennsylvania Gov. Tom Ridge, an abortion-rights supporter, and Connecticut Sen. Joe Lieberman, the Democratic vice presidential pick in 2000 who now is an independent.
Since Obama clinched the nomination in early June, speculation has swirled about the prospective No. 2s.
CBSNews.com tracks the veepstakes buzz and ranks the top contenders. See who's number 1!
Names mentioned have included Sen. Jack Reed of Rhode Island, a national security expert who traveled with Obama to Iraq and Afghanistan; former Georgia Sen. Sam Nunn, another foreign policy authority; and New Mexico Gov. Bill Richardson, a prominent Hispanic with vast international experience.
While Obama's search committee reviewed its list of potential candidates during the past several weeks, the campaign was busy building the vice presidential staff operation that includes chief of staff Patti Solis Doyle, who was Clinton's campaign manager, and spokesman David Wade, who was 2004 Democratic nominee John Kerry's traveling press secretary. Rick Siger, advance director for Kaine's campaign, came on to oversee the travels of the eventual pick, increasing buzz that his former boss could be the likely choice.
The drama of Obama's impending announcement drew dozens of new reporters to travel with his campaign Monday. They listened in vain for clues as Obama held a subdued meeting with several dozen women in New Mexico on the topic of wage discrimination, sticking to his word that he wouldn't say anything about the decision until his announcement.
Obama was more animated Monday afternoon at a raucous town hall meeting, where Richardson introduced him. He praised Richardson as one of the nation's best governors, but otherwise gave no hint of the governor's future status.
Even as they were kept out of the loop on the decision, Obama's staff debated who would make the right choice. Many said if the candidate asked them, they would suggest Biden because of his foreign policy experience and strong debate skills; Sebelius because she's a respected Washington outsider who has won a Republican state; or Bayh because he can appeal to Democrats uneasy about Obama and could help him win Indiana.
Each candidate could pose problems, too. An Obama-Sebelius ticket would be especially light on international experience. Bayh supported the Iraq war; Obama did not and has said that is a leading indicator of judgment.
Republicans are already envisioning their response to a Biden pick - Obama is so inexperienced that he had to pick someone with a 26-year record in Senate. Biden has spent a longer time on Capitol Hill than McCain, they point out, which doesn't exactly represent the kind of change Obama says is needed in Washington.
Biden was far from the speculation Monday; he traveled over the weekend to Georgia to meet with President Mikhail Saakashvili and discuss the country's military clash with Russia.
Other potential vice presidential prospects also seemed to be going about business as usual. Sebelius was traveling to Michigan on Tuesday to help boost Obama's support among women there, while Kaine helped unveil a bust of explorer Meriwether Lewis in Virginia's old House chamber on Monday.