A San Francisco supervisor Tuesday asked for a hearing on concerns that the city could be on the hook for upwards of $20 million in expenses for the America's Cup sailing races later this year.

San Francisco has pledged to spend around $30 million on the races, which start in July. That money was supposed to be recouped by private donors but fundraising has stalled, Supervisor John Avalos said.

The America's Cup Organizing Committee, the group tasked with raising money for the races, "has not lived up to its pledge," Avalos said.

The supervisor said he is requesting a hearing be held in the next couple weeks on the status of the fundraising and the possibility of the city being reimbursed for a portion of the amount not raised.

"It seems like there's been a real obfuscation of the impacts and benefits" of the races, Avalos said.

He said he hoped the city does not end up "subsidizing this event for the wealthiest people in the world."

Mayor Ed Lee told reporters Tuesday that he has recently joined the effort to raise the needed money but acknowledged, "It's never easy to do this."

He said the fundraising problems were due in part to perception that the race, brought to San Francisco by Oracle CEO Larry Ellison, "is someone else's race and not ours."

But Lee said, "It's really San Francisco's race. We're going to get the benefits of all these people coming."

The city was initially estimated to have as much as $1 billion infused into local businesses and services, but those estimates have been downsized as the America's Cup has been reduced to three teams.

However, Lee said the downsizing of the race could mean the city also ends up spending less, reducing the amount of money that needs to be raised.

The America's Cup races begin with the Louis Vuitton Cup between July 4 and Aug. 30, the Red Bull Youth America's Cup from Sept. 1-4 and then the America's Cup Finals from Sept. 7-21.

More information about the races can be found online at www.americascup.com.