WASHINGTON (AP) - Presidential candidate Barack Obama said Friday the running mate he has chosen - but has not yet announced - had to meet three standards to join the Democratic ticket: Prepared to be president, able to help him govern and willing to challenge his thinking.
Those criteria did little to narrow the guessing game as Obama prepared for a massive rally in Illinois on Saturday to present his No. 2 to the nation and undertake a pre-convention tour of battleground states. He planned to disclose his choice through text messages to supporters, perhaps as early as Friday.
"Obviously, the most important question is: Is this person ready to be president?" Obama said in an interview aired Friday on "The Early Show" on CBS. Second, he said, was: "Can this person help me govern? Are they going to be an effective partner in creating the kind of economic opportunity here at home and guiding us through some dangerous waters internationally?"
And, he added: "I want somebody who is going to be able to challenge my thinking and not simply be a 'yes person' when it comes to policymaking.
The Illinois senator was widely thought to be seriously considering Virginia Gov. Tim Kaine, Gov. Kathleen Sebelius of Kansas and Sens. Joe Biden of Delaware and Evan Bayh of Indiana. Although it appeared unlikely, Obama's vanquished rival Hillary Rodham Clinton still could emerge as his No. 2., and there were dark horse candidates who could emerge.
Among them: Texas Rep. Chet Edwards, a favorite of House Speaker Nancy Pelosi, GOP Sen. Chuck Hagel of Nebraska, who traveled with Obama to Iraq and Afghanistan, Massachusetts Sen. John Kerry, the 2004 Democratic presidential nominee, or Democratic Sen. Chris Dodd of Connecticut.
One person who had been vetted for the position told The Associated Press there had been no contact from Obama or his campaign about the decision.
Republican and Democratic officials said both Obama and GOP rival John McCain were capable of making wild card picks that would surprise their backers.
Several GOP officials said Friday that McCain had not settled on a running mate - nor offered the job to anyone - although former Massachusetts Gov. Mitt Romney and Minnesota Gov. Tim Pawlenty were under serious consideration. It's likely McCain will wait to see who Obama selects before picking his running mate.
Officials said the campaign also was preparing for an "unconventional" nominee, an indication that oft-mentioned former Pennsylvania Gov. Tom Ridge, an abortion-rights supporter, or Connecticut Democrat-turned-independent Joe Lieberman still could be in the running. That category also could include non-politicians who McCain deeply admires, such as Gen. David Petraeus, the top U.S. commander in Iraq.
Two officials close to Romney said he had not been offered the job. Pawlenty batted away questions Friday in a CNN interview, saying, "I'm sure he'll make a wonderful choice for our party and for our country and we'll just have to wait until next Friday to find out the answer to those questions."
The Arizona Republican is expected to announce his choice between the Democratic National Convention that begins Monday and the GOP convention beginning Sept. 1 in St. Paul, Minn. He might do it on Friday, Aug. 29, the day he turns 72 and a day after Obama accepts his own nomination, but no plans are set.
Speculation about McCain's choice has been fueled by plans for pre-convention rallies planned in Ohio, Michigan and Pennsylvania. Romney is a Michigan native; Ridge is from Pennsylvania. A dark horse, Rob Portman, is a former Ohio congressmen. But all three states could have been chosen simply because they are key, electoral-rich battlegrounds.
On Thursday, Obama spent part of the day campaigning with Kaine. West Virginia Gov. Joe Manchin said Kaine told him although he hadn't heard anything from the Obama campaign on where he stands at the time, "he really thinks he has a chance at the short straw."
"I've made the selection, that's all you're gonna get," Obama told The Associated Press.
Kaine and Obama met privately with the governor's staff for 15 minutes at a Richmond hotel. Afterward, Kaine said he would let the Obama campaign speak about whether the candidate asked him to be his No. 2. But two people close to Kaine said the governor was still in the dark.
Kaine plans to fly Friday night directly from Virginia to Denver, site of next week's convention, three people with knowledge of the governor's travel plans said. The plans could be changed if Kaine is told he needs to fly to Springfield, Ill., for the Saturday rally instead.
Biden had a family gathering at his home Thursday afternoon, with his wife Jill, niece Missy Owens and son Beau, Delaware's attorney general, coming and going past reporters staked outside.
Sebelius, campaigning for Obama in Iowa, said she would leave the announcement to the campaign.
Bayh worked in his Capitol Hill office and later spent time at his home in Washington. He left wearing shorts and a baseball cap but told reporters outside he had no news to share. "Not tonight, sorry," he said.
Two long-shots appeared out of the running: Former Georgia Sen. Sam Nunn's spokesman said he would be traveling internationally until Monday and Sen. Jack Reed of Rhode Island, a national security expert, told an AP reporter that he was not Obama's choice.
Associated Press writers Bob Lewis in Virginia; Nedra Pickler in Chicago; Beth Fouhy in Emporia, Va.; Larry Messina in Charleston, W.Va.; Randall Chase in Greenville, Del.; Mike Glover in Des Moines, Iowa; Ray Henry in Jamestown, R.I.; and John Hanna in Topeka, Kan., contributed to this report.
(Copyright 2008 by The Associated Press. All Rights Reserved.)