With the clock ticking down, the Oakland City Council on Tuesday gave a revamped group planning the Coliseum City stadium development a 90-day extension of its exclusive negotiating agreement with the city.

Council members privately told us they were encouraged by the team’s 11th-hour addition of new deep-pocket investors being represented by San Diego asset manager adviser Floyd Kephart, chairman of the board of Renaissance Cos. Kephart is expected to take the lead role in the newly reconstituted group, New City Development LLC.

We’re told the group expects to have a developer with a national reputation signed on within 60 days, as well as approvals from the Raiders and NFL — plus the city and Alameda County — to begin detailed planning for a new football stadium. The stadium would be the centerpiece of a development that would also include housing, retail, offices and perhaps a ballpark for the A’s.

For some time, council members had said they were reluctant to extend the exclusive deal unless Raiders owner Mark Davis signed on to the agreement. He still hasn’t, but some council members told us they’re at least satisfied that Davis is “comfortable” with the new investment group and wants the negotiations to proceed.

One notable exception was mayoral candidate Rebecca Kaplan, the only council member voting to oppose extending the agreement. She said the council hadn’t received the “key, overdue information” they were promised.

“Revitalizing the Coliseum is essential to the economic future of our city,” Kaplan told us in a prepared statement. “But to date, we’ve received no deal terms, no financing proposal and no identified developer.”

It’s also no secret that Kaplan has had a close working relationship with Oakland A’s owner Lew Wolff, who has repeatedly expressed his opposition to be part of any Coliseum City deal.

Following the council’s closed door vote to extend the talks, Mayor Jean Quan called the action “an important step forward in the work we kicked off three years ago” to keep the Raiders playing in Oakland. She also said she expects the negotiating team to reach out to the A’s and the Warriors as well. “There is room for all three teams in this project,” she said.

The A’s, while insisting they have no desire to be part of Coliseum City, separately are exploring building a replacement ballpark somewhere in the vicinity. The Warriors have announced plans to move to San Francisco’s Mission Bay.

Meanwhile, the Coliseum Joint Powers Authority, the city-county body that oversees the sports complex, is expected to vote next month on handing former Oakland City Manager Robert Bobb a $25,000-a-month contract to look at the merits of Coliseum City or any other stadium or ballpark deal that might come along.