Wouldn't it make sense that public officials be required to take drug tests?

Many who are public employees are required to take drug tests, why not our Congressmen, Senators or President/VP? These should be regularly administered and highly public (results I mean). It only makes sense. We, the citizens, have entrusted much in our elected officials, don't we have a right to insist that they be drug free? Who would oppose, except those taking illegal drugs?