The debut for the newly-minted ticket will take place outside the Old State Capitol in Illinois while hundreds of miles to the west, carpenters, electricians, sound stage gurus and others transformed the Pepsi Center in Denver into a made-for-television convention venue.
Tucked away in one corner were thousands of lightweight rolled cardboard tubes, ready-made handles for signs bearing the names of the Democratic ticket - once the identity of Obama's running mate was known.
While Obama decided against adding Clinton to his ticket, he has gone to great lengths to gain the confidence of her primary voters, agreeing to allow her name to be placed in nomination at the convention and permitting a roll call vote that threatens to expose lingering divisions within the party.
"In naming my colleague and friend Sen. Joe Biden to be the vice presidential nominee, Sen. Obama has continued in the best traditions for the vice presidency by selecting an exceptionally strong, experienced leader and devoted public servant," Clinton said in a statement. "Sen. Biden will be a purposeful and dynamic vice president who will help Sen. Obama both win the presidency and govern this great country."
Biden, 65, first was elected to represent Delaware in 1972. Obama was 11 at the time; half the people living in the U.S. were not born when Biden arrived on Capitol Hill.
Biden's wife and daughter were killed in a car accident a few weeks after he was first elected, but two sons survived serious injuries in the crash. Biden commuted home to Wilmington daily to care for them, a practice he continues to this day. The oldest son, Beau, is now Delaware's attorney general and a National Guard member whose unit is being deployed to Iraq in October.
Biden got another scare 10 years ago, when two brain aneurysms kept him out of the Senate for several months.
This week Biden returned from a trip to the former Soviet state of Georgia that he made at the invitation of the embattled country's president, a well-timed reminder of the value he could bring to Obama's ticket.
Fighting between Georgia and Russia has only increased the sense that Americans will turn to the candidate they believe will be a strong international leader.
Sen. John McCain, the presumptive GOP nominee, brings a military background and a leading role on the Senate Armed Services Committee. Obama only has served three years in Washington, but Biden is chairman of the Senate Foreign Relations Committee.
Polls suggest the race between Obama and McCain is tightening, and Obama is responding by stepping up his attacks in speeches and commercials targeted to key states. Obama has never been entirely comfortable going negative, but Biden is always ready for a fight.
Obama could have been describing Biden when he said in a speech Tuesday that he wants his running mate to be "somebody who is mad right now" about the state of the economy, an independent spirit who will speak out when Obama's wrong and help him through major issues.
During the Democratic primary, when he also sought the presidential nomination, Biden often made the most memorable impression in debates even though he was barely registering in the polls. He got big laughs for accusing Republican candidate Rudy Giuliani of mentioning three things in every sentence - "a noun, a verb and 9/11" - and also leveled barbs at Obama, questioning his experience.
He said he didn't think Obama was ready to be president yet, saying it's "not something that lends itself to on-the-job training." He offended some blacks when on the first day as an official presidential candidate he tried to compliment Obama as "the first mainstream African-American who is articulate and bright and clean."
Biden dropped out of the race after a poor showing in the Iowa caucuses.