LOS ANGELES — Los Angeles could lose and win its Olympics gamble, ending up with the 2028 Games it never sought and the costly prospect of retooling its multibillion-dollar plans for more than a decade into the future.

In an atmosphere of uncertainty, International Olympic Committee leaders began three days of meetings and site visits Wednesday to weigh LA’s plans for the 2024 Games in its showdown with rival Paris. A decision is scheduled for September.

The two cities are the only remaining bidders after a string of embarrassing withdrawals by Rome, Hamburg, Germany, and Budapest, Hungary. Looking to avoid another messy competition, the International Olympic Committee has made an unusual proposal to award the next two Olympics, 2024 and 2028, one to each city.

LA organizers have publicly winced at the 2028 option — as with Paris, they say they are bidding only for 2024. The consolation prize would not only be a disappointment in LA, it would leave the city with challenges from maintaining public interest to recasting deals for stadiums, arenas and housing that have been in the works for months and even years.

Remaking LA’s plan for 2028 “would take an awesome amount of work because all of the conversations, all of the negotiations, all the plans, have been built around 2024,” said Gary Toebben, who heads the Los Angeles Area Chamber of Commerce.

“There is a tremendous amount of expense involved in another four years,” he said.

By some accounts, the IOC would have to amend its rules to impose a split decision, and it’s not clear if there are votes to make the change. Additionally, expanding the September decision to include 2028 could anger countries that had plans to bid on those Games.

“There may be cities out there that did not bid for 2024, thinking they would bid for 2028. Those would be the aggrieved cities,” said Barry A. Sanders, chairman of the Southern California Committee For The Olympic Games, a nearly 80-year-old civic group that supports the Olympics movement.

Another potential snag: If LA is awarded the 2028 Games, it apparently would need to renegotiate and extend financial guarantees approved by the city and state to cover potential shortfalls in 2024.

Gov. Jerry Brown signed legislation in September that puts California taxpayers on the hook for up to $250 million if Los Angeles is awarded the 2024 Games and they run over budget.

“Are they willing to give a guarantee that goes out 11 years?” asked Sanders, referring to 2028. “Financial matters over 11 years are hard to predict.”

IOC members are spending three days in Los Angeles touring proposed venues, including the historic Rose Bowl and Los Angeles Memorial Coliseum. Both were used in the 1932 and 1984 Games hosted by the city.

Speaking to reporters in downtown Los Angeles, leaders of the city’s 2024 bid talked up the financial benefits of bringing the Games to Southern California.

After anxiety over taxpayer costs helped derail Boston’s 2024 Olympic bid, organizers in stand-in Los Angeles made its tight budget a highlight of its proposal. It requires no new construction of permanent venues, instead relying on existing structures and arenas, all serving an IOC mandate for less expensive games that require less new construction.

Los Angeles is pledging to stage the Games for $5.3 billion, which would be around one-third of what Tokyo is projecting to spend for 2020. Recent Olympics have become synonymous with skyrocketing costs — the 2014 Sochi Olympics have been called the most expensive of all time.

“It’s not just about the 2024 Games, it’s about sustainability and relevancy of every Games after,” Mayor Eric Garcetti said.

Angela Ruggiero, chief strategy officer for the bid and vice chair of the International Olympic Committee athletes’ commission, noted that LA’s bid includes $50 million for spending on improving the athletes’ experience.

“We can do this because we don’t have to build a single new venue,” she said.

A glance at LA’s sprawling proposal across Southern California provides insight into the job involved in extending it for four years.

There are arrangements for housing at the University of California, Los Angeles, and a satellite village at the University of California, Riverside, for athletes who would compete in rowing events at Lake Perris; sailing off Long Beach, table tennis in downtown LA, and volleyball in Santa Monica. For 2028, those would all have to be pushed forward.

On the flip side, a delay might have benefits for LA.

For example, the city is in the midst of a transit-building boom, and four more years would mean more time to build rail lines.

City Council President Herb Wesson said Tuesday that he had not discussed a potential shift to 2028 though he didn’t rule out the possibility the city could accept it.

“I don’t know what IOC is going to do,” Wesson said in an interview. “If it happens, then we’ll deal with it.”