COLUMBIA, SOUTH CAROLINA: The four top GOP presidential contenders met in a debate just two days before South Carolina's critical primary begins. In a race each candidate views as vital to his chances, polls show Bob Dole with a comfortable lead over Pat Buchanan, with Steve Forbes and Lamar Alexander battling for third place. As the focus of the presidential race shifts to the south, each candidate hopes to use a strong showing in South Carolina as a springboard to primaries in Georgia on March 5 and Florida on March 12. Dole spent much of Thursday's debate defending himself from charges by the others that he was a chronic tax raiser. Even as Alexander began to defend himself for a spot attacking Dole for supporting $320 billion in tax increases, Forbes rushed to pile on. "The ad is misleading," he said, and suggested that the actual number was closer to $1 trillion. "Don't malign my integrity here," Dole snapped after one particularly testy exchange with Forbes. For his part, Buchanan was hit hard by the other three on his protectionist trade stance. But despite accusations that the tariffs that Buchanan supports would destroy a South Carolina revived by foreign investors like BMW, Buchanan held his ground. Dole in the end tried to move the focus away from his competition and toward a common foe: "This is about defeating Bill Clinton in 1996 and there is one candidate who can beat Bill Clinton in 1996 and that is Bob Dole."