But De La Fuente, who has run for mayor twice before and hasn't ruled out running again in the future, will remain a powerful figure at Oakland City Hall, as the council also voted unanimously to elect him vice mayor.
The position is largely ceremonial, but De La Fuente will act as mayor when Oakland Mayor Ron Dellums is unavailable.
Larry Reid was elected council president pro tem, which means that he will serve as president if Brunner is unavailable.
Brunner, who has been on the City Council since 1997, wasn't immediately available for comment.
De La Fuente said in a phone interview, "I support my friend Jane Brunner 100 percent."
But he said being council president will be "a very challenging job" in the wake of Oakland's serious budget deficit.
De La Fuente has been Oakland's only council president since the position was created in 1998, when the city switched to a strong mayor form of government.
De La Fuente said he understands that many people are speculating that the reason he announced on Sunday that he wouldn't seek a sixth two-year term as president is that he didn't have enough votes to continue in the position.
But he insisted, "This was absolutely my decision and I decided for many reasons not to seek another term."
De La Fuente declined to elaborate but said they might become more apparent on Tuesday, when Brunner will announce the City Council's committee assignments.
