The snickering began as soon as the shock from the 1994 election wore off. The Republicans had won back the Senate, and Alfonse D'Amato would become chairman of the Senate committee looking into Whitewater. Al D'Amato? The name was synonymous with sleaze. Would anyone take an ethics investigation under his direction seriously? Probably not--or at least not without the help D'Amato has received from a New Jersey prosecutor with an ethical record that is the reverse image of his own.