In a polite but contentious exchange, the California gubernatorial candidates question each other's fitness to lead the state and of being beholden to campaign contributors.The candidates vying to be California's next governor had their first face-to-face debate Tuesday evening, a polite but contentious exchange in which Republican Meg Whitman and Democrat Jerry Brown largely stuck to their campaign stump scripts, questioning each other's fitness to lead the state and accusing their opponent of being beholden to campaign contributors.