By Kathy Bergen

LA JOLLA, Calif. -- Chicago on Friday unveiled a potential vision for its hosting of the 2016 Summer Games: a track-and-field stadium --enormous but not necessarily permanent -- situated along the lakefront, within sight of downtown.

"We will be offering the most compact Summer Games in an unparalleled urban setting on the shores of our magical lakefront with our stunning skyline as the backdrop," said Michael Segobiano, Chicago's director of marketing.

Segobiano's descriptions, made during an interview, represented the first official but still incomplete picture of what a Chicago Olympics might look like, as the city stepped into a five-way race to become the U.S. candidate to host the Games.

In private sessions at a hotel with the U.S. Olympic Committee board of directors, representatives from Chicago and the other cities -- Los Angeles, San Francisco, Houston and Philadelphia -- made preliminary pitches.

Chicago kept most details of its plan under wraps, but it gave hints that a focal point of the Games, a track-and-field venue that must seat at least 75,000, would be located near downtown.

Given the expected use of Soldier Field and McCormick Place as other venues, the site is very likely to be south of Soldier Field.

Segobiano suggested that whatever stadium is built for the Games may not remain in that form afterward. Such a plan would not be unprecedented. Parts of the main Olympic stadium in Atlanta for the 1996 Summer Games were razed after the Games concluded, and what remained became part of Turner Field, home of the Atlanta Braves baseball team.

"We need to build a track-and-field facility, and it will be state-of-the-art, world-class," said Segobiano. "When the Olympics are over, part of the facility will be left as a legacy to the Olympic Games and to track and field."

Many of the Olympic facilities would be geographically compact, Segobiano said, which would be a big selling point to Olympic officials.

In a news conference, Mayor Richard Daley declined to flesh out the "elegant solution" for a venue to accommodate track and field and the opening and closing ceremonies, which he had alluded to on Thursday. Daley and other officials also declined to divulge other details about event venues or the Olympic Village, citing both the competitive situation and a request from the USOC.

With Daley's presence in California at the presentation, Chicago appeared to be aggressively pursuing the Games. Still, an evaluation committee announced Thursday by the mayor's office is charged with analyzing whether it makes economic sense for the city to proceed with a bid.

At a news conference, Daley and two heavyweights from Chicago's business community talked up the city's ability to fund major projects through public-private ventures, the most recent being Millennium Park.

"It's almost a no-brainer," said Miles White, chairman of Abbott Laboratories. "The private community and business will fully support and finance this."

"No taxpayer money will be used," added Patrick Ryan, head of the evaluation committee and executive chairman of insurance giant Aon Corp. "And the benefits will be tremendous. People will come in and spend a lot of money."

The city's pitch is based on the theme, "The American Experience, with Chicago Style."

"It's an opportunity to showcase Middle America," Daley said.

While Chicago officially faces competition from four other cities, observers say it's likely to be a three-way horse race between front-runner San Francisco, Olympics veteran Los Angeles and Chicago.

"On a scale of all involved, I think Chicago is second or third," said Robert Livingstone, producer of GamesBids.com, a Toronto-based news site focusing on the Olympics bid process.

San Francisco, which has the dazzling aesthetics that appeal to the IOC, was runner-up to New York in the competition to be the U.S. bid for the 2012 Games. New York ultimately lost out to London.

San Francisco Mayor Gavin Newsom said the venues were too spread out in the city's 2012 bid. This bid will be more San Francisco-centric, he said, and all venues will be within 45 minutes of the Olympic Village.

Los Angeles, which hosted the Olympics in 1984 and 1932, also will be a tough rival.

The city already has almost all necessary venues, which would enable it to keep construction costs low and possibly produce a surplus that could be shared with the Olympic movement. The city's proposal is expected to include a financial package that will appeal to Olympics officials, though officials declined to discuss finances on Friday.

In addition, the city plans to tap the talents of Hollywood heavyweights.

On the downside, Los Angeles will have to fight a been-there, done-that perception among Olympics officials. "It's not a novel bid for the IOC," said Livingstone.

Los Angeles Mayor Antonio R. Villaraigosa spoke to that issue Friday, saying 70 percent of the venues are new since 1984.

Chicago is running later than some rivals in terms of getting its organizational structure in place, but it is viewed as a strong candidate for a number of reasons, including its strong visual image and its lakeside location, a plus for sailing and other events.

"It has a strong political leader, a concentration of facilities and lodging, excellent transportation, both at the airport and locally, a strong corporate base and strong cultural facilities," said Marc Ganis, president of Sportscorp Ltd., a Chicago-based sports facilities and franchise consulting firm.

Bob Ctvrtlik, USOC vice president/international, praised the city. "Chicago definitely brought quality to the bid process," he said. "They've got innovation, they are doing a lot of things right, but you've got to get 60 votes [from IOC members], or you don't get to win the bid."

USOC officials indicated they could whittle down the field of five contenders in as soon as three weeks. The committee is still undecided whether to proceed with a bid from the U.S., but should make that decision by autumn or next March at the latest.

The site of the 2016 Games will be chosen by the International Olympic Committee in 2009.