his rival by noting that the North Carolina senator had failed to vote in the 1994 election that gave Republicans control of Congress for the first time in 40 years.

At another point, Kerry rebuffed an Edwards charge by acridly insisting that his rival "should do his homework."

The hourlong morning debate saw Kerry, Edwards, Rep. Dennis J. Kucinich of Ohio and the Rev. Al Sharpton of New York spar almost as much with the three media questioners as with one another.

Kerry and Edwards tussled most directly on three fronts: trade, the cost of Kerry's agenda and Edwards' claim that he will bring more-sweeping change to Washington.

The tougher tone taken by Edwards may have reflected what's at stake for him in the Super Tuesday contests, which include primaries in California,New York, Ohio, Georgia and Maryland.

Although Edwards said again Sunday that he would remain in the race regardless of Tuesday's results, many Democratic leaders believe he will have difficulty sustaining a credible candidacy if he cannot topple Kerry in at least one -- and probably more -- of the states.

With polls showing Kerry holding leads of at least 2 to 1 in New York and California, Edwards' best chances in the major contests may be Ohio and Georgia. But new surveys in those states have shown him trailing.

Although Edwards did not open any new lines of attack in Sunday's debate, he broadened familiar arguments and framed others in much more barbed terms.

One of the sharpest exchanges came when Edwards repeated his frequent assertion that he was more likely