The third-place finisher in San Diego's mayoral election endorsed former Police Chief Jerry Sanders (search) on Thursday, throwing his support to a fellow Republican in a runoff against a Democratic city councilwoman and surf shop owner.

Steve Francis (search), a businessman who poured about $2 million into his campaign, won 24 percent of the vote in Tuesday's primary, trailing Sanders, who finished with 27 percent.

Democrat Donna Frye (search) received 43 percent of the vote in the nonpartisan race, but fell short of the majority she needed to avoid a Nov. 8 runoff against Sanders.

Dick Murphy (search) resigned as mayor of the nation's seventh-largest city this month amid widening federal investigations of the city's pension fund. His interim replacement resigned days later after a jury convicted him of federal corruption charges.

Francis said Sanders would get tough with municipal labor unions and has proven adept at turning around troubled organizations.

Sanders, 55, held positions in the local United Way and American Red Cross chapters after being police chief from 1993 to 1999.