Mark Sanford’s victory in the special election in South Carolina’s 1^st District tell us little new about the 2014 elections. But it does serve as a reminder about one important factor in American politics that shouldn’t be ignored when the midterms roll around: partisanship.

At the end of the day, most Republican voters in the district decided to vote Republican, even though their nominee had more than his share of warts.

Democrat Elizabeth Colbert Busch might well have won in a more competitive district, but she could not convince Republican voters — conservative Republican voters — that she was a safe choice or that Sanford was unacceptable.

Mitt Romney carried the district with 58.3 percent of the vote in 2012, and John McCain won it with 56.1 percent in 2008. Sanford’s percentage of the vote in the special election fell only slightly below those levels, at 54 percent of the vote, according to the South Carolina State Election Commission.

But it’s also worth noting that Colbert Busch failed to carry Charleston, which often goes Democratic.

Romney lost the county to President Barack Obama 50.8 percent to 48 percent last year, and Democrat Vince Sheheen carried the county by almost the same margin against Republican Nikki R. Haley in the 2010 gubernatorial race. In 2008, Democrat Linda Ketner carried the county by more than 10,000 votes against the incumbent, Republican Rep. Henry E. Brown Jr.

Sanford’s victory probably takes the seat off the political table for 2014 and reinforces something that I have already believed for months: The House playing field will be relatively narrow next year.

(Read more Stu Rothenberg on the 2014 elections in Roll Call: Ranking Potential Flips for 2014 House Rematches)