OAKLAND — City officials finally have their hands on a preliminary financing plan for a new Oakland Raiders stadium that, if workable, could keep the Raiders in the East Bay, but chase away the Oakland A’s.

The financing plan, one of several reports submitted Monday by San Diego-based businessman Floyd Kephart, is bound by a confidentiality agreement and has not yet been released, Kephart wrote in an email.

Although Kephart has until Aug. 21 to provide a final stadium proposal, top city officials and Raiders owner Mark Davis have described the preliminary financing plan as a potential make-or-break moment in the long-running effort to transform the sprawling 120-acre Coliseum site into a privately-developed urban center with sports facilities, apartment buildings, offices, shops and a hotel.

The NFL is demanding that Oakland produce a workable stadium plan for the Raiders by the end of this year or risk losing the team, which is collaborating on a stadium plan with the San Diego Chargers in the Los Angeles suburb of Carson.

City officials have always pitched a new baseball stadium as part of the project known as Coliseum City, but Oakland A’s co-owner Lew Wolff told this newspaper on Sunday — the day Kephart was initially required to submit his reports — that his team had no interest in sharing the site with the Raiders.

“We have thoroughly investigated things and there is no good way to put two brand-new venues at the Coliseum site,” Wolff said. He added that it would be difficult for both teams to generate the corporate sponsorships and premium seating required to privately finance new stadiums.

Raiders owner Mark Davis also has been cool to sharing the site, saying last month that he wants O.Co Coliseum, which is home to both teams, torn down before a new football stadium is built.

Oakland Mayor Libby Schaaf, reached by phone Monday, said she hadn’t seen Kephart’s proposal and declined to comment on Wolff’s pointed rejection of a shared Coliseum site — the only place in Oakland he says he is considering building a new ballpark.

Later in the day, Schaaf said in an email statement that the city is “analyzing the viability of the submission from Mr. Kephart,” and taking a “multipronged approach so we have as many options available as possible for stadium development without the use of City of Oakland general fund dollars.”

The Raiders have estimated the cost of a new 55,000-seat football stadium at $900 million.

With the team and the NFL offering $500 million, Kephart must come up with a proposal to fully finance stadium construction without an outright public subsidy. Funding mechanisms used for other stadiums have included hotel tax surcharges, ticket surcharges, and stadium parking surcharges.

In addition to the stadium financing plan, Kephart said he also submitted required reports Monday on the feasibility of the housing and commercial components of the project, along with proposals on dealing with the nearly $100 million of debt remaining on the Coliseum and public financing of needed infrastructure improvements expected to cost about $150 million.

If public officials don’t like the plan, they can opt not to renew their agreement with Kephart, who has claimed to have hedge fund connections, to finance the project when it expires in August.

With the NFL demanding quick results, stadium experts said Oakland will have to keep working on a Raiders deal even though it could hinder its chances of getting a new baseball stadium built.

“You’ve got to play both out on a parallel track until you can find out if you can get one of them for certain,” said Marc Ganis, president of the Chicago-based consulting firm SportsCorp Ltd. “It’s foolish to drop one if you don’t know whether the other will materialize.”

Staff writer John Hickey contributed to this story.

Contact Matthew Artz at 510-208-6435.