Rio de Janeiro's bid to take the Olympics to South America for the first time in 2016 gained further momentum Wednesday when the Brazilian city came off best in a technical evaluation of the four candidate cities.
Chicago, meanwhile, came in for some pointed negative comments - including its financial guarantees and public transportation - and Madrid and Tokyo also took some direct hits from the International Olympic Committee.
The 98-page report from the IOC's evaluation commission was released exactly a month before the IOC vote in Copenhagen on Oct. 2.
"The IOC report is a real boost to the Rio bid," bid president Carlos Nuzman told The Associated Press. "They have provided a very strong confirmation of our games plan and vision. It is fair to say Rio has a very positive report, and possibly the most favorable. We didn't have any red points."
The report, which did not grade or rank the cities, is intended only as a guide for IOC members and is unlikely to sway the final decision. Intangible factors, including geopolitical issues, always play a major role when the IOC's 100-plus members cast their secret ballots.
The report is based on visits by the evaluation commission in April and May, and was issued two months after more than 90 members listened to presentations from the bid cities in Lausanne, Switzerland, where most of the key issues were already covered.
In what shapes up as a tight race, the final presentations on the day of the vote could be crucial. Whether President Barack Obama goes to Copenhagen to lobby for Chicago could be decisive, just as Tony Blair helped secure the 2012 Olympics for London when he met IOC members in Singapore in 2005 and Vladimir Putin traveled to Guatemala City in 2007 to push Sochi's winning bid for the 2014 Winter Games.
"Clearly having President Obama there would be an advantage," Chicago bid leader Patrick Ryan said, "particularly since each of the other cities are saying that their leaders will be there."
Ryan said all the issues raised in the IOC report have or can be resolved, and he expressed confidence in Chicago's prospects of bringing the Summer Olympics back to the U.S. for the first time since the 1996 Atlanta Games.
"I think we got a very good score," Ryan told the AP in a telephone interview. "We feel the wind is really at our back for the last 30 days. It's going to go down to the wire. Nobody knows who's going to win this. We have as good a chance as anybody."
For the moment, though, things seem to going Rio's way.
The Brazilian city made a big impression with members at the June meeting in Lausanne, arguing the case for the Olympics to be held on a new continent. Africa and Antarctica are the only other continents that have not hosted the games.
The IOC report cited Rio as embracing the "potential power of the games to transform a city, a region and a country" and said the Olympics would leave "a lasting and affordable legacy."
The Rio bid is the most spread-out and most expensive of the four, with a budget of $11.1 billion for capital investments associated with the games.
"The commission is confident that the growing Brazilian economy would be able to support the necessary infrastructure development needed for the delivery of the 2016 Games," the IOC report said.
The IOC also cited Rio's vision of using sport as a "catalyst for social integration" and said the bid had strong public support, financial guarantees from all levels of government, and knowledge and experience from the city's hosting of the 2007 Pan American Games.
But Rio also came in for some matters of worry.
With Brazil scheduled to host the 2014 World Cup, the report expressed "some concern" about marketing the Olympics in the same four-year period.
While citing Rio's "public safety challenges," the IOC said new anti-crime programs were "already showing positive results."
The report said transportation plans in Rio would be "critical" and that urban infrastructure projects would need "careful management and monitoring."
The IOC said Rio had an "insufficient" number of hotel rooms, and plans to use four villages and six cruise ships would "require particular attention in both the planning and delivery phases."
Among the issues under scrutiny for Chicago has been financial guarantees. Unlike other bid cities, Chicago's candidacy is not underwritten by the federal government.
"Chicago 2016 has not provided a full guarantee covering a potential economic shortfall of the OCOG (Olympic organizing committee) as requested by the IOC," the report said, adding that Chicago had instead proposed a capped guarantee of $750 million which presents a "risk" in the event of a larger deficit.
Since the IOC visit in April, however, Chicago Mayor Richard M. Dally has pledged to sign the host city contract, requiring the city to take full financial responsibility and the proposed $4.8 billion operating budget.
"The issues will be resolved in the next few days," Ryan said. "The city of Chicago has a very strong credit rating. We expect final approval from the city council soon."
The IOC praised Chicago's compact venue plans along the downtown waterfront, and minimum travel time for athletes, but noted that the equestrian, shooting, road cycling and mountain biking venues were relatively far away.
The report also singled out the "well-designed and compact lakefront Olympic village" but noted that, at the time of the commission's visit, full financing guarantees for the complex had not been provided.
The IOC also said Chicago's use of temporary or scaled-down venues "increases the element of risk" to the organizing committee, and said transportation could be a "major challenge" because it would involve more than doubling the peak commuter traffic on the Metro commuter rail service.
The report said there was a need for "clearer delineation of roles and responsibilities" between the city and organizing committee, and said Chicago's budget - including $1.83 billion in sponsorships - is "ambitious but achievable."
Tokyo, which held the Olympics in 1964, drew praise for it compact venue plan and government financial backing but was cited for a "relatively low level of public support" in an IOC opinion poll from February showing support of only about 55 percent of the city's residents.
"We have worked very hard to respond to IOC feedback since the evaluation committee's visit to Tokyo in April," Tokyo bid leader Ocher Kong said in a statement. "We are confident we already have a plan that will fully satisfy all challenges and demonstrate our ability to be their most reliable and dependable partner."
Madrid, bidding for the second time in a row after losing the 2012 Games to London, was lauded for its compact layout and readiness of existing venues. But the report criticized Madrid's bid for not showing "a full understanding of the need for clear delineation of roles and responsibilities, including financial, between different stockholders..."
"I'm left with a bittersweet taste," Madrid bid leader Mercedes Coghen said. "Sweet because they know that our city is ready. Bitter because we weren't able to tell them better. We're not good communicators. We need to work on this."