SAN FRANCISCO  Theresa Sparks, a candidate for the San Francisco Board of Supervisors, is running on what some might see as a conservative platform: she is pro-development and anti-loitering, pro-police and anti-grime. She has been endorsed by the mayor, the city’s firefighters’ union and the county deputy sheriff’s association.

But that is not what sets Ms. Sparks apart; it is her past. Until a decade ago, Ms. Sparks was a man, before a gender reassignment surgery. And while her sex may have changed, her politics did not.

“This district really needs someone with a strong business background, a strong economic background and a really wide diversity of experience,” said Ms. Sparks, who is an experienced engineer, a United States Navy veteran and the former chief executive of Good Vibrations, a sex toy company. “And I’m really the only person who has that in this race.”

If elected, Ms. Sparks would be the first transgender supervisor in San Francisco  the liberal enclave where Harvey Milk was elected as one of the nation’s first openly gay officials in 1977, and perhaps the only place where Ms. Sparks might be considered right-of-center.