The role of the first lady

President George W. Bush has been warming up crowds at campaign rallies lately with the applause line: "I'm going to give you some reasons why I think you need to put me back in office, but perhaps the most important reason of all is so that Laura will be First Lady for four more years." The crowd cheers, presumably expressing their preference for the president's wife over Theresa Heinz Kerry. And although the First Lady has no official duties, it's clear that the electorate pays attention to the people married to the candidates. But what does the American public expect from the First Lady? An activist? Someone who stays out of political fray? Or somehow both things at once?