Fighting Argentina's Fat Cats.(Elisa Carrio)

It is difficult to imagine Elisa Carrio as a teenage beauty queen. The 46-year-old Argentine congresswoman is famously unkempt in her grooming and dress habits--and in a society that places a high premium on fashion and physical beauty, the plump, crucifix-sporting Carrio has made her mark in part through sheer frumpiness. If people don't like the way she looks, then that's their problem. Carrio happily describes herself as "fat, peripheral and provincial."

As recently as 2001, it was even more difficult to imagine Elisa Carrio as the next president of Argentina. But as the debt-saddled South American country lurches toward general elections tentatively scheduled for April, Carrio is vying for the top spot in the polls with the leading candidate of the ruling Peronist party. The constitutional-law professor's one-woman crusade against corruption in government has struck a chord among millions of disenchanted voters, who ascribe many of Argentina's economic ills to rampant pocket-lining by mainstream politicians. Carrio's political ascent is all the more remarkable because the populist legislator ...