San Francisco’s regional bid to host the 2024 Olympics was tweaked Wednesday on the eve of an expected decision by the U.S. Olympic Committee, adding a proposal to have the Opening and Closing ceremonies — and track-and-field events — at a hoped-for new stadium in Oakland.

“I’m excited about partnering up for the bid,” newly sworn-in Oakland Mayor Libby Schaaf said Wednesday. “The Olympic committee is interested in supporting a stadium project that would be a permanent facility — a legacy facility — for the A’s or the Raiders, although I think it would more likely be with the Raiders.”

The original proposal from the San Francisco bid committee was to have a $350 million temporary stadium in Brisbane serve as the signature venue. It would be designed to be torn down afterward. That may still wind up being the case if San Francisco is ultimately awarded the Games and the Oakland venue doesn’t come about.

The Raiders and East Bay officials have been trying for years to hammer out a new stadium proposal, with funding being a crucial sticking point. The Olympics may provide the impetus and additional funding to get things done, although exactly how the financing would work is unresolved.

“We believe the idea of including a major track-and-field arena and stadium being built in Oakland that could accommodate the Raiders, that that is a good combination,” San Francisco Mayor Ed Lee said. “It’s the kind of legacy we saw the city of London leave with the East End when they were trying to revitalize that area. This could be that very possibility. I’m excited for Oakland for that reason.”

Lee and Schaaf were on a call with U.S. Olympic officials on Wednesday to discuss the new proposal.

“It was welcomed,” Lee recounted. “It was very welcomed by the USOC, saying by all means measured, this enhances your bid. This is what they said to us.”

San Francisco is one of four U.S. cities vying to be the country’s pick to compete against an international field to host the 2024 Summer Olympics. The other U.S. finalists are Los Angeles, Boston and Washington, D.C.

U.S. Olympic officials are expected to make a decision on the U.S. candidate city at their meeting in Denver on Thursday. The International Olympic Committee is expected to pick the host of the 2024 Games in 2017.

“I’m enthusiastic, but there’s some stiff competition,” Lee said. “I’m not saying anything against the other cities, but I think L.A. is a pretty strong contender.”

Chronicle columnist

Phil Matier contributed

to this report.

John Coté is a San Francisco Chronicle staff writer. E-mail: jcote@sfchronicle.com Twitter: @johnwcote