As the race between Hillary Clinton and Barack Obama continues to tighten, GOP candidate John McCain is enjoying more overwhelming support than ever, according to the latest Washington Post-ABC News national poll. Clinton's 47%-43% lead over Obama falls within the poll's margin of error, with no clear sign of who will be picked by supporters of former candidate John Edwards.
Meanwhile, McCain has surged to 48% support among probable GOP voters, neatly doubling Mitt Romney's 24% and tripling Mike Huckabee's 16%. Given his party's winner-take-all rules, McCain could lock in his candidacy with a successful result on Super Tuesday. For Obama and Clinton, who have both stepped up their last-minute campaign efforts, the outcome is too close to call. (Read more Super Tuesday stories.)