Barack Obama and his future running mate are expected to campaign together Saturday in the same city where the Illinois senator launched his bid for the White House.

It is not clear whether Obama will announce his vice presidential selection before that. Numerous Democratic sources have told FOX News that Obama will make his pick known on Thursday or Friday.

But a senior Obama adviser confirmed to FOX News that the Democratic ticket will be together Saturday in Springfield, Ill., narrowing the window for Obama to reveal his selection.

A joint appearance there would be fitting for a candidate who values the symbolism of the locations and dates he chooses for major events. His first joint appearance with Hillary Clinton was held in the town of Unity, N.H. He's giving his nomination acceptance speech on the 45th anniversary of Martin Luther King Jr.'s "I Have a Dream" speech.

And the Illinois Democrat kicked off his campaign in Springfield early last year in front of the former Capitol where Abraham Lincoln once served. That's where he's expected to speak Saturday.

The Illinois senator kept his plans to himself Tuesday. The campaign publicly said only that the Saturday event would mark the kickoff of his trip going into the Denver convention.

But in a Florida address to the Veterans of Foreign Wars Tuesday Obama praised Sen. Joe Biden, the Senate Foreign Relations Committee chairman thought to be among the contenders, for proposing an additional $1 billion of reconstruction projects in the Republic of Georgia after the Russian invasion.

Biden later batted away the speculation, telling reporters Tuesday, "I'm not the guy."

Obama seemed to give another clue when he referred to his running mate as "he" during a speech to a Raleigh, N.C., Tuesday evening. He made the comment while describing the qualities he's looking for in a No. 2.

"Let me tell you first what I won’t do.  I won’t hand over my energy policy to my VP, without knowing necessarily what he’s doing.  I won't have my VP engineering my foreign policy for me. The buck will stop with me, because I will be the president," Obama said. "But here’s what I do want from my VP. I want somebody who has integrity, who’s in politics for the right reasons, I want somebody who is independent."

There are two women commonly mentioned as potential running mates: Hillary Clinton and Kansas Gov. Kathleen Sebelius.

But an Obama aide said Obama's use of the pronoun, "he," doesn't mean anything.

Much of the speculation, though, surrounds the timing of the announcement. A senior Democratic official familiar with Obama's deliberations said it was extremely unlikely the running mate choice would be revealed Tuesday or Wednesday, as some reports suggested.

Democrats close to the situation expect the announcement to come Thursday. The common speculation is that the unveiling will occur in Chicago. The theory behind this notion is that a Chicago event near the campaign's headquarters would allow for greater secrecy of such an event.

Aides close to Obama refuse to say whether the vice presidential selection has already been made, but concede the window of opportunity is closing to finalize the choice.

Obama was believed to have narrowed his list to Biden, Virginia Gov. Tim Kaine, Indiana Sen. Evan Bayh and Sebelius.

In Warren, Mich., Tuesday, Sebelius wouldn't say if she expects to be chosen and said she doesn't know the timetable for naming Obama's choice. "I think a week from tomorrow we will all know," Sebelius said.

While it seemed increasingly unlikely that he would choose his vanquished rival, some Democrats speculated Monday that he could pull a surprise and pick Clinton.

Clinton no longer appears a viable option, though many Democratic strategists say they won't rule her out entirely until the decision is announced.

Obama planned to campaign Wednesday with former Virginia Gov. Mark Warner and on Thursday with Kaine.

Some Democrats say they believe if Obama picks any of the established U.S. senators it will suggest his campaign is lacking Washington experience and gravitas and, in the case of Bayh, Biden and John Kerry, needs to bolster the ticket's credibility on foreign policy and national security. This would also be true if Obama selected former Georgia Sen. Sam Nunn, a southerner who has carved out a reputation as a national security thinker and innovator.

Nunn, though, is currently out of the country and does not expect to be asked to be on the ticket, according to an aide. The aide said he has no plans to even attend the Democratic National Convention.

"(The Obama campaign has) many things to do before the convention and sharpening the message against John McCain is only part of it," a top Democratic strategist said. "The pick will tell us how Obama thinks he's doing."

Asked about rumors that the announcement could come as early as Tuesday, Obama spokeswoman Jen Psaki said, "Anyone who thinks they know or says they know how or when the vice presidential pick is being made or announced doesn't know what they're talking about."

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.

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 Democratic vice presidential prospects also seemed to be going about business as usual. Sebelius traveled 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.

Meanwhile, John McCain plans to announce his vice presidential pick on Aug. 29, his 72nd birthday, in Dayton, Ohio, FOX News has learned.

Planning for the McCain announcement began weeks ago, and while it remains subject to change, is scheduled to come the day after the Democratic National Convention ends and two days before the start of the Republican National Convention.

Sources have said for weeks the 29th is the most logical date given the calendar. Those same sources have long said Ohio is a must-win state for McCain and the Buckeye State would be among the first states the newly announced GOP ticket would visit.

As it stands now, McCain will hold a 10,000-strong rally in Dayton the day after Obama accepts his party’s nomination in Denver.

Democrats expect Obama's choice to affect GOP rival McCain's selection of a running mate.

McCain's 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.

Also mixed in the list of names is former Arkansas Gov. Mike Huckabee. He said Tuesday he hasn't been approached by McCain but he wouldn't reject the offer. He added that it would "disrespectful" to suggest who the choice should be.

FOX News' Carl Cameron, Major Garrett and The Associated Press contributed to this report.