NORTH CAROLINA -- Leading up to the midterms, three North Carolina congressional races were rated as toss-ups, with the potential of flipping from Republican to Democrat. 

That did not happen, with all three remaining in Republican control.

Republican incumbent George Holding bested Democratic challenger Linda Coleman in North Carolina's 2nd district. Democrat Kathy Manning fell to Republican congressman Ted Budd in the 13th district.

And in the 9th district, which was left open after incumbent Republican Robert Pittenger lost in the primary, Mark Harris bested Dan McCready.

Catawba College professor and political analyst Michael Bitzer says there are many factors at play that caused the potential flips to not happen.

He notes that in both the 2nd and the 13th districts, the "power" of incumbency seemed to help.

The shape of the districts, he says, also likely had an impact. A panel of federal judges have labeled the state's congressional district map unconstitutional, saying they were gerrymandered to unfairly favor Republicans over Democrats.

"The Democratic wave was in North Carolina, it just wasn’t high enough to reach over the walls that the Republicans have constructed around these districts," Bitzer said.

Of the three "toss-up" races, the 9th district was the closest. The district runs from the Charlotte suburbs to Fayetteville along the South Carolina border. Harris dominated in Union County. McCready was just not able to make up the difference in the more Democratic Charlotte suburbs of Mecklenburg County.

"It was really a battle between Union and Mecklenburg for the two candidates. It’s just McCready’s spread wasn’t as great as Harris's was in Union," Bitzer said.

In the end, North Carolina's congressional delegation remains split as it was before: 10 Republicans and three Democrats.

The question is, with another round of redistricting on the horizon and the demographics of the state continuing to change, how long can that last?