A new legal effort to force California’s governor and attorney general to defend Proposition 8 in court may have some political potency, but is unlikely to win in court, legal observers say.

A conservative group on Tuesday filed with the state’s 3rd District Court of Appeal in Sacramento a petition for a writ of mandamus to force Attorney General Jerry Brown and Gov. Arnold Schwarzenegger to defend Proposition 8 — which the two office holders have publicly said they would not do.