OAKLAND, Calif.—Oakland's top non-elected city official said she is resigning from her position.

City Administrator Deanna Santana confirmed to the San Francisco Chronicle on Sunday that she is leaving her job but declined to say why.

Santana's abrupt departure comes at a time where she has sparred with not only with Mayor Jean Quan, but also with the City Council and other city officials. She also has been openly searching for another job.

"I believe I've served the city well for the time I've been here, and the mayor and I have agreed on a mutually beneficial exit strategy," Santana told the newspaper.

Quan said Monday that assistant city administrator Fred Blackwell will take over on Tuesday. The mayor is scheduled to deliver her state of the city address on Thursday.

Santana, 43, has been Oakland's city administrator for nearly three years after serving as a deputy city manager in San Jose. Santana was at the helm when the city evicted hundreds of protesters from the Occupy Oakland encampment outside City Hall in 2011; assisted with closing a $58 million budget deficit; and witnessed the departure of three police chiefs and other various city officials.

Recently, Santana has been looking to depart as well, becoming a finalist for top administrator jobs in Dallas and Phoenix. She was passed over for both jobs. Still, some colleagues praised Santana for steering the city through tough times.

"Deanna is one of the smartest, brightest people I've known," Larry Reid, a councilman and vice mayor, told the Oakland Tribune. "I think her leaving is a loss for the city even with the job search."

Santana also had strained relations with Robert Warshaw, a federal court-appointed monitor overseeing the embattled police department whom she accused of sexual harassment in 2012.

A federal judge dismissed Santana's claim and last month granted Warshaw broad authority over the police department, which has failed to fully implement reforms ordered after a 2003 lawsuit against four police officers accused of misconduct.

Quan in a written statement Monday described Santana as a "tireless worker and leader."