By all accounts it's going to be a close one. CBS News correspondent Charlie D'Agata reports that with just one day to go before the big vote, many judges on the International Olympic Committee are still undecided about where the Summer 2016 Games should be held; Rio de Janeiro, Tokyo, Madrid, or Chicago.
First Lady Michelle Obama found herself on the campaign trail again, charming Olympic judges at a cocktail party Wednesday night in the hope of bringing the 2016 Summer Olympics to the Windy City.
"Everything about this bid speaks to what this city has to offer," Mrs. Obama said of her hometown.
President Obama will join his wife in Copenhagen Friday in the final push to bring the Olympics to U.S. soil again.
But House Minority Leader John Boehner chastised the president, saying Mr. Obama was "going to go off to Copenhagen when we've got serious issues here at home that need to be debated."
British bookmakers put Chicago's odds of winning the bid at 4 to 5, followed closely by Rio de Janiero at 13 to 8, then Tokyo and Madrid.
Rio is doubtless the toughest challenger. It would be the first time the Olympic Games were held in South America.
Tokyo and Madrid both argue they are better prepared to host the games.
But, Olympic officials say the "Obama factor" may clinch the deal.
"I think it can only help, and certainly can't hurt," said IOC member Dick Pound.
On Friday, committee members will vote out one of the candidate cities, and the thinking is that this is likely to go to three rounds of voting.