The top two Democrats in the California gubernatorial campaign have gone to war with each other over their political adverts. Billionaire environmentalist Tom Steyer, whose campaign is attempting a last-minute surge against Democratic frontrunner Xavier Becerra, have each threatened legal action against the other. Steyer on Saturday published a commercial titled "Risky," which sought to connect Becerra to the criminal convictions of two former senior aides and suggested he could face legal jeopardy.