For his part, Republican rival John McCain 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.

Since Obama clinched the nomination in early June, speculation has swirled about the prospective No. 2s.

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.