The host winner ceremony begins around 11:30 a.m. Chicago time on Friday. The announcement is expected to come around 11:55 a.m.
Anticipation is building throughout the Chicago area and in Denmark.
In a just a few hours Copenhagen convention center will come alive with activity as President Obama arrives, doing a personal favor for Mayor Daley by making a personal pitch for Chicago.
It had to be tough to concentrate. Michelle Obama, Oprah and Mayor Daley joined the King of Spain, the president of Brazil and Tokyo's team for a night of ballet when all they really care about is whose left standing when the music stops Friday.
"There's not another thing we could have done. To know you've stepped out with the best people possible, the best presentation possible. Sincere, the most authentic, that's all you can do," said Oprah.
Chicago's bid backers lined Copenhagen's most famous canal to show their support as IOC members arrived by barge for the opening ceremony.
Earlier in the day, reps from all of the cities made last minute pitches to the people who will pick the 2016 host city on Friday.
"What Rio is offering in fact is something new. New country. New continent. New people," said Carlos Roberto Osorio, Rio 2016 secretary general.
"The final 24 hours we want to present Chicago as a partner for the IOC. A city and group that they can trust," said Doug Arnot, Chicago 2016 senior vice president.
Mrs. Obama has met one-on-one with dozens of voters. She tells them the Olympics can demonstrate her husband's eagerness to engage the world.
White House Chief of Staff Rahm Emanuel gave ABC7 a preview of what the President will tell IOC members at the final presentation.
"His main point is why America reaching out to the world would be the right response in the sense of why Chicago has the capacity and the United States has the desire to make these a world class, world event in the city of Chicago," said Emanuel.
"It is the icing on the cake and the icing on the cake as we all know is very important, very essential," said Sam Ramsamy, IOC member, South Africa.
Twelve people will be on stage for Chicago's final presentation. They include President Obama, the first lady and Mayor Daley; representing Chicago 2016 are Pat Ryan, Lori Healey, and Doug Arnot; Olympian Bryan Clay and Paralympian Linda Mastandrea will also be there as well as the United States' two IOC members and the chairman and vice president of the U.S. Olympic committee.
As strong as Chicago's showing has been here, our city is still something of an unknown underdog. Madrid, Rio and Tokyo have all bid for the Games before. Their people are better known by IOC voters, some of whom have never even been to Chicago.
Leaders meet with Danish royals
Leaders from the other countries going for the games mingled with Danish royals ahead of Friday's vote.
On Thursday afternoon they arrived at the Royal Palace in Copenhagen for an official lunch with dignitaries from around the world. They included Brazilian president Luiz Ignacio Lula da Silva, Tokyo governor Shintaro Ishihara and Spanish king Juan Carlos and Queen Sofia. They were welcomed by Queen Margrethe II of Denmark and her husband, Prince Henrik.
How the IOC vote works
The 106 members of the IOC are the ones who will decide which city wins the Games. They'll cast their votes until one city emerges with a majority victory.
The president of the IOC doesn't vote, and members of countries that have a bid city in the race do not vote until their city is ruled out, meaning in the first round 98 people will be voting.
Each round of voting is an elimination round until one city can claim the majority vote.
For demonstration purposes only, let's assume no city gets a majority in the first round vote, and Tokyo has the least number of votes. Tokyo would no longer be a contender, and the two IOC members from Japan would now be able to vote in round two.
With three cities left in the race, the IOC members vote again, once more with no majority winner.
If there's a tie for second place, those 2 cities have their own elimination round, but in this case, let's say Madrid received the fewest votes.
Madrid would be out and its one member can now vote.
We're down to the nail-biter so many have predicted: the showdown between Chicago and Rio de Janiero that may or may not materialize.
The votes are cast electronically one more time, and if Rio loses to Chicago, Chicago wins the right to host the 2016 Summer Olympic and Paralympic Games.
All the voting is electronic and by secret ballot, so the rounds could be over in less than an hour.
The membership of the IOC is quite an exclusive group, in the first round of voting Friday, more than 10 percent of those voting can be called royalty.
New report out on Chicago's bid
A new report out Thursday that assesses Chicago's land use and infrastructure plans comparative to pat host cities says Chicago has not fully laid out nor thought through how infrastructure changes would take place or affect its citizens. Click here to read the report.
One of the other cities also hoping to host the 2016 Games is feeling a little confident and is planning a big party. In Rio de Janeiro, a stage is being built on the beach in anticipation of the big announcement. Bands will be performing there. The public has been invited to come and cheer on Rio's bid. Brazilian officials have declared Friday an optional public holiday so that more people can take part in the party.
ABC7 will provide complete coverage of the announcement. A timeline of coverage can be found here. Ben Bradley will report live from Copenhagen starting Tuesday.
On October 2, the host city winner announcement is expected at about 11:55 a.m.
All of events will also be streamed live on our Web site, abc7chicago.com.