Los Angeles and Chicago are now the only remaining U.S. candidates to host the 2016 Summer Olympics after San Francisco abandoned its bid Monday.

The failed negotiations between the city of San Francisco and the 49ers to build a new stadium last week hinted that the city’s bid to host the Olympics might be dead, something the city confirmed on Monday.

“There’s been a tremendous amount of uncertainty created around the stadium process which has made our bid untenable,” said Peter Ragone, spokesman for San Francisco Mayor Gavin Newsom.

John York, owner of the 49ers, told city officials last week he was breaking off negotiations for a new stadium at Candlestick Point and was considering a move to near-by Santa Clara. The 49ers said in a statement Monday they had encouraged the bid committee not to build its entire proposal around a new 49ers stadium at Candlestick Point.

Scott Givens, managing director and chief executive officer of the bid committee, said the 49ers’ decision created a “perceptual gap” that hurt the city’s reputation in the eyes of the Olympic committee.

Givens added that the committee mulled various options — including modifying At & T; Park, home of San Francisco Giants; expanding Kezar Stadium in Golden Gate Park; or building a new stadium at Candlestick Point without the 49ers’ help – all of which may have saved the bid — but all proved unworkable, he said.

San Francisco’s loss can only help Los Angeles and Chicago, one of which will be the American candidate when the United States Olympic Committee decides in December to nominate a city.

The candidates have to present a plan to the USOC by March 31, with the winner chosen in April. Los Angeles, the host of the 1932 and 1984 Summer Games, is the only American candidate with a stadium currently in place, the Coliseum.

Chicago has proposed building a new stadium in its Washington Park area, which would be the centerpiece of an Olympics that would be based around Lake Michigan and downtown. The Chicago 2016 organizing committee has not given specifics of how the privately financed venue would be paid for, other than to say the city would make the USOC feel comfortable about its plan.

The U.S. winner will then compete with the international field, which includes: Madrid; New Delhi; Prague, Rio de Janeiro, Rome and Tokyo, in landing the 2016 Summer Games. The Summer Olympics will be in Beijing in 2008 and London in 2012.