LAUSANNE, Switzerland — The four cities bidding for the 2016 Olympics took their case directly to the voters on Wednesday, stressing the backing of their government leaders and promising financial security for their multi-billion-dollar projects.

Chicago, Tokyo, Madrid and Rio de Janeiro made formal presentations to members of the International Olympic Committee in a crucial test before the final vote in Copenhagen on Oct. 2.

"I'm a lucky man not to be obliged to vote," IOC president Jacques Rogge said after the presentations. "It's going to be a very difficult choice for my colleagues. I can say very clearly the four bid cities are capable of hosting superb games."

The closed-door sessions at the Olympic Museum were attended by 93 of the IOC's 107 members — a strong turnout showing intense interest in what shapes up as a tight race between candidates from four continents.

At a time of global recession, budget plans and financial guarantees came under extra scrutiny in the 45-minute presentations and 45-minute question-and-answer sessions. Rio even brought the head of Brazil's central bank to reinforce its economic message.

"There was definitely an emphasis on financial considerations," Rogge said.

Chicago, seeking to take the Summer Games back to the United States for the first time since the 1996 Atlanta Olympics, led off the proceedings with a six-member delegation headed by bid leader Pat Ryan and Mayor Richard M. Daley.

Rogge said Daley confirmed he would sign the Olympic host city contract if Chicago gets the Olympics, requiring the city to take full financial responsibility for the games. Chicago had previously raised concerns about some of the guarantees required in the standard contract.

"The mayor has clearly indicated that he would sign the host city contract," Rogge said. "We have only one host city contract. There is no amendment to the host city contract from the IOC."

Chicago showed a video featuring Valerie Jarrett, a senior adviser to President Barack Obama, in which she reiterated the chief executive's support for the bid. She highlighted Tuesday's announcement that Obama is forming a White House Office of Olympic, Paralympic and Youth Sport.

Bid officials hope that Obama — a former Illinois senator from Chicago — will travel to Copenhagen for the IOC vote.

Jarrett's appearance "is reflecting the president's commitment," Ryan said. "I thought she expressed the president's thoughts extremely well."

Asked why Obama himself did not appear in Wednesday's video, Chicago venues and operations director Doug Arnot said the IOC had asked the cities not to use "celebrities and dignitaries" in the presentations.

"To be a good partner you have to follow instructions, so we did so," he said.

That didn't stop Tokyo and Madrid from showing videos of the Japanese and Spanish prime ministers and Rio from screening a message from the Brazilian president.

As with all U.S. bids, the Olympics in Chicago would not be underwritten by the federal government. Bid leaders told the IOC they have their own secure public-private guarantees.

"The city of Chicago has put up guarantees of $500 million and the state of Illinois has legislation for $250 million," Ryan said. "We are very comfortable that we can bring from the private sector additional resources that will take the guarantees up to the $2 billion range."

Three members of the group "No Games Chicago," which argues the games are bad for cities financially and can displace thousands of people, set up a stand outside the museum and distributed documents opposing the bid.

Mario Pescante, a senior Italian member on the IOC executive board, said the Chicago presentation was a step above previous U.S. bids.

"I have seen lots of presentations by American cities over the years," he said. "This time it was different. They were more accessible and low-profile. It was important to stress the sports issues. In the past, it was more Hollywood style."

While Chicago has long been viewed as a favorite, Ryan downplayed any front-runner status.

"We don't believe it is ours to lose," he said.

Rio, seeking to take the games to South America for the first time, showed a video message from Brazilian President Luiz Inacio Lula da Silva that was recorded two days ago in Geneva.

"He stated the full commitment of the Brazilian government with all guarantees," Rio bid secretary general Carlos Roberto Osorio said.

Brazilian central bank president Henrique Meirelles gave assurances of the country's financial stability.

"Brazil is expected to come out of this crisis growing, in a sustainable way," he said. "Our investments are coming back to Brazil. All of that provides assurance that Brazil is in a position to entertain this (hosting Olympics) and take advantage of the games economically."

Rio officials showed a world map marking all the places where the Olympics have been held — with a big blank space for South America. They also stressed that Brazil was capable of hosting the 2014 World Cup and 2016 Olympics back to back.

Tokyo, which staged the Olympics in 1964, emphasized the bid has already secured $4 billion.

"Tokyo offers the most secure financial foundation for the games," bid leader Ichiro Kono said. "Let there be no mistake: $4 billion is in the bank today."

It's the first time the IOC has arranged such a forum for bid cities. With IOC delegates barred from visiting bid cities since the Salt Lake City scandal, this gave bid teams a chance to explain their plans directly to the voters and answer their questions.

On Thursday, the cities will set up exhibition rooms at a Lausanne hotel where they can show videos and meet with the members individually.