SAN DIEGO -- All three San Diego ballot propositions -- including a measure giving the mayor the power to hire the internal auditor -- passed by large margins, according to election returns released by the Registrar of Voters Wednesday.

Proposition C, the most contested measure, which gives the mayor the authority to appoint the city's internal auditor, was backed by 64 percent of voters.

The internal auditor's job is to scrutinize the city's books and ensure the accuracy of what is reported to Wall Street.

Under Proposition C, however, the mayor doesn't have the power to fire the city auditor, as is the case now.

Instead, the auditor will be governed by a three-member audit committee made up of City Council members. The committee would have the ability to fire the auditor.

Opponents argued that Proposition C gives the mayor too much influence over a position they maintain should be independent from management, likening it to a "fox guarding the henhouse."

"The mayor is management, and as management should not have a role in selecting the city's independent auditor," Councilman Tony Young said at a recent rally against Proposition C.

The "No on Prop C" effort was also being spearheaded by Councilwoman Donna Frye, who has said the city needs an auditor who will be "independent and will represent the people."

Supporters maintained that Proposition C creates an appropriate check and balance between the mayor and the City Council.

Mayor Jerry Sanders said it brings "balance between the executive and legislative branches in the functioning of financial matters."

The auditor selection method is backed by Stanley Keller, an attorney hired by San Diego to act as its monitor on financial matters following a Securities and Exchange Commission investigation.

The SEC sanctioned the city in 2006 for failing to fully disclose to potential investors the scope of its more than $1 billion pension shortfall, and equally large retiree health care obligations.

Proposition C also makes permanent the City Council's independent budget analyst position and defines the roles of the chief financial officer and city treasurer.

The two other ballot measures that passed were not challenged.

Proposition A will exempt police, firefighters and lifeguards from being outsourced under the city's managed competition program, which was authorized by more than 60 percent of San Diego voters in 2006.

Proposition B will require the City Council to place on the ballot in 2010 a series of charter amendments to make permanent San Diego's switch to a strong-mayor form of government.

Ultimately, in 2010 voters will be asked to consider adding a ninth City Council seat and increase the number of votes it takes to override a mayoral veto, which can now be done with a simple majority.

The strong-mayor form of government was approved in 2002. It gave the mayor duties previously held by the city manager, like the ability to hire and fire department heads and prepare the annual budget.