Ben Knotts of the Examiner asks that question:

A current poll from Real Clear Politics has the presumed GOP nominee, Mitt Romney, consistently leading PresidentObama in the fall election, since May 15th, 2012.

Prior to May 15th, polls showed President Obama continually leading his GOP opponent in North Carolina., but since that day, Mitt Romney - the former Governor of Massachusetts - has not failed to carry the support of the state.

What caused the shift in numbers? The issue of same-sex marriage provides a reasonable explanation.

On May 8th, North Carolina voters banned same-sex marriage by amending their state constitution to only recognize marriage as a union between one man and one woman.

On May 9th, President Obama endorses same-sex marriage - putting himself at odds with North Carolina voters on the controversial issue.

On May 12th, Governor Romney addressed social-conservatives at Liberty University declaring that marriage is only between one man and one woman - putting himself in agreement with North Carolina voters on the issue.

By May 15th, Obama's lead has shifted to Romney, and Romney has held the lead consistently ever since.