With the support of Governor Friend Richardson and publisher Joseph R. Knowland, a leader of the conservative faction of San Francisco Bay Area Republicans, Warren was appointed as the Alameda County district attorney in 1925. Warren faced a tough re-election campaign in 1926, as local Republican boss Michael Joseph Kelly sought to unseat him. Warren rejected political contributions and largely self-funded his campaign, leaving him at a financial disadvantage to Kelly's preferred candidate, Preston Higgins. Nonetheless, Warren won a landslide victory over Higgins, taking over two-thirds of the vote. When he ran for re-election again in 1930, he faced only token opposition.