Barack Obama has decisively won North Carolina's Democratic primary, boosting his campaign after a recent rocky patch.
His rival Hillary Clinton claimed a slim victory in Tuesday's other vote at Indiana and pledged to go "full speed on to the White House".
The two Democrats have been locked in a drawn-out battle to stand against Republican John McCain in November's presidential vote.
Correspondents say Mrs Clinton needed to do better to catch up with Mr Obama, whose lead is said to now look increasingly unassailable.
Senator Obama told cheering supporters that regardless of who was eventually chosen as the Democratic nominee, the party would be united for November's election.
The polls were the last two major electoral prizes before the Democratic nomination convention in August.
Altogether, 187 delegates were at stake in the two states, nearly half the pledged delegates left. Six primaries remain before voting ends in a month.