Romney, now the presumed GOP nominee, had 856 delegates going into Tuesday's primaries, according to The Associated Press, which is still short of the 1,144 he needs to lock up the GOP nomination. Just over 100 delegates were up for grabs on Tuesday, in North Carolina, Indiana and West Virginia. Romney won all three contests, but will still be short of the magic number.

The state's primary was not the only notable aspect of the ballot on Tuesday. North Carolina also considered a referendum that would define marriage as being between a man and a woman, during a week when the topic of same-sex marriage became a talking point in the presidential campaign.

Vice President Biden spoke out about his view on the topic, ramping up the pressure on Obama to clearly define his position.

Obama does not support same-sex marriage, although he does support civil unions, and has called his views "evolving."

Under attack on the issue, Obama campaign spokesman Ben LaBolt said in a statement released Tuesday that Romney “hasn’t evolved — he has regressed.”

The Romney campaign said its candidate is for traditional marriage between a man and woman.