(marketwatch) - An eleventh-hour surge in polls by Sen. Barack Obama over Sen. Hillary Clinton is shaping up to make "Super Duper Tuesday" a dramatic showdown between the contenders for the Democratic nomination, while John McCain is handily leading his Republican rivals in a survey taken before the 24-state contest.

With 52% of the Democratic delegates and 41% of the Republican delegates at stake, Tuesday's election-season smackdown promises higher stakes and a payoff bigger than this past weekend's Super Bowl. Big winners may have their party nominations all but locked up after the returns are in from contests all over the country, from Alaska to West Virginia and plenty of points in between.

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