I'd say the break-even point is about a 4% margin of victory nationally. Which is pretty impressive for someone like Obama in North Carolina.
I would even say less than that at this point. The trend in NC, more Yankees coming down, growing minority population, etc, probably moves it to that point as it is (if not less). The convention in Charlotte perhaps diminishes the national margin a bit as well.
Of course candidates also have an impact. Despite the northerners moving down, Huckabee still appears to be a stronger candidate in NC than Romney, so Obama would need to defeat Huckabee by a larger margin nationally to take NC than he would need to beat Romney nationally to take it.
I would be surprised if NC is more than 2-3% more GOP than the national average, and wouldn't be the least bit surprised if it winds up being one of if not the closest states to the national average.
