Alameda County leaders want out of the pro sports business and have told Oakland officials that they are ready to sell their stake in the Coliseum complex, which houses the Raiders, A’s and Warriors.

The move would be a major game changer in the negotiations to keep the three teams playing in the East Bay — talks that have often been contentious and confusing for all parties involved.

“It’s been extremely challenging to negotiate a deal with the city, the county, two public entities and three sports teams,” county Supervisor Nate Miley, vice chairman of the joint Oakland Alameda County Coliseum Authority, which oversees the sports complex, told us Wednesday.

“So let’s just get out of this and let the city negotiate whatever deals it wants,” Miley said. “Because, frankly, Oakland is going to benefit much more from this than the county.”

If the city is interested — and there’s every sign it is — Oakland and Alameda County officials would have to agree on the value of the five-decade-old property. Then the city would have to come up with the many millions of dollars it would take to buy out the county’s share.

Miley said county representatives delivered the message Wednesday to Oakland Mayor Libby Schaaf and NFL executives at a meeting at the Raiders’ Alameda headquarters. The full county Board of Supervisors has told staffers to get to work on the details, although a vote would be required to make it happen.

Wednesday’s meeting had been called so the city could give a progress report on its efforts to help the Raiders build a new stadium at the Coliseum site, a plan that many fear is floundering.

San Diego developer

The city has hooked its hopes to San Diego businessman Floyd Kephart and his partners from New City Development, who want to build a $900 million football-only stadium on the Coliseum site. What Kephart and friends don’t have is a financing plan, and their feelers for public money to pay for infrastructure improvements have gone nowhere.

On Monday, Miley told a Los Angeles radio station that it was a mistake for the county to have gone along with the city’s negotiating agreement with Kephart. The supervisor doesn’t think Kephart can deliver on a deal.

The county first signaled its interest in selling several months ago, soon after Schaaf was elected mayor in November. And apparently the reaction was positive.

Since then, the county has done an appraisal on the Coliseum complex. While no figure has been disclosed, it’s believed to be worth hundreds of millions of dollars.

“This is in everyone’s best interest,” Miley said of a county sale. “The teams have been frustrated by the current structure, so it benefits everyone to have a single public entity that they can deal with.”

Schaaf issued a statement saying the city looked forward to exploring with the county how to “responsibly move toward sole ownership of both the land and the existing sports venues. Such a move would ultimately help simplify current discussions with our sports teams and streamline negotiations for any future development.”

Saving franchises

City Councilman Larry Reid, who serves on the Coliseum Authority, said the city has long known of the county’s desire to sell its stake, adding, “I think it makes sense.

“It makes it easier to save one if not both franchises in question,” Reid said, referring to the Raiders and A’s.

“The question is, what kind of deal can be structured, and where can we find the money to buy the county out?”

One major issue that would have to be worked out is the debt the city and county have carried since the Coliseum overhaul of the mid-1990s, which lured the Raiders back from Los Angeles. The city and county each pay $11 million a year to service the debt, which isn’t scheduled to be paid off until 2026.

According to Miley, the county loses money on the Coliseum every year. That’s not the case for Oakland, he said, because the city gets money from parking taxes and various other sources.

That has led to friction between the city and county, which has made unsuccessful overtures to Oakland officials to share more of their revenue from the complex.

The Raiders aren’t the only team whose future is complicated by the Coliseum’s multiheaded management arrangement. The A’s say they can’t make any moves to build a new ballpark at the Coliseum site until the Raiders figure out their future. If the Raiders get their way and build a new football-only stadium on the site, the A’s will have to leave.

History of tension

There’s already a history of tension between Oakland and the county over the A’s. Last year, after the Coliseum Authority negotiated a lease extension with the team, the City Council balked — infuriating the team and prompting then-baseball Commissioner Bud Selig to give the A’s the green light to leave town.

Ultimately, cooler heads prevailed and the A’s got their extension.

As for the Warriors, they’re already making plans to leave Oakland for a new arena in San Francisco’s Mission Bay. That may be something no combination of East Bay governments can head off.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross typicallly appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or e-mail matierandross@sfchronicle.com. Twitter: @matierandross