Fundamentals matter in American politics, and Tuesday reaffirmed what political studies have shown: There’s a direct relationship between a congressional district’s partisan makeup and its vote totals.

Unlike presidential elections, where economic conditions and personal factors can have a bigger impact on the outcome, political scientists know that the “normal vote” — the portion of the vote a congressional candidate is expected to receive based on the district partisanship — is the best predictor of congressional election results.

Just six months back, GOP presidential candidate Mitt Romney won an 18-percentage-point victory over Barack Obama in the 1st Congressional District.

Based on Romney’s success in November, we would expect Sanford to receive about 58 percent of the vote.

But Sanford wasn’t your typical candidate, and his 2009 sex scandal posed serious questions about his ability to make a political comeback.

According to one study, sex scandals cost lawmakers about 5 percent in the subsequent election after the scandal, so taking Romney’s vote and subtracting 5 percent would result in about 53 percent for Sanford. He won with 54 percent Tuesday.

What can we expect from Sanford in his return Congress? In terms of his legislative record, Sanford will be a staunch conservative. Period.

As just one example, if we extrapolate Sanford’s voting record in the 103rd, 104th and 105th Congresses (1993-99) to the 112th Congress (2011-13), Sanford would rank as more conservative than 91 percent of Republicans.

Why do we expect Sanford to vote so conservatively? The answer again can be found in the district’s partisan make-up.

In the 112th Congress there were 10 representatives from districts where Obama received exactly 40 percent of the vote, just like he did in South Carolina’s 1st District. In nine out of 10 of these districts, these representatives were more conservative than the average Republican, and most were considerably more conservative.

Another big question is whether Sanford will get his seniority back. While he may in fact get credit for his past service, there is no seniority rule. Rather, there’s something called a seniority norm.

Republican leaders may feel that Sanford is a distraction and make him start as a freshman. This happened to Democrat Cynthia McKinney when she returned to Congress in 2005.

Finally, how long can we expect Sanford to serve voters in the 1st District? On average, representatives serve for five terms, or 10 years.

He already has served three full terms, and we should expect to see Sanford in the political spotlight for several more years, at least.

And with 90 percent of incumbents winning re-election, this seat is likely Sanford’s as long as he wants it.

In sum, catchy narratives about electoral dynamics often miss the mark. It may not be sexy, but what matters in explaining Sanford’s Tuesday win — and how he might govern — is the partisan makeup of the 1st District.

Gibbs Knotts is professor and department chairman of political science at the College of Charleston. Jordan Ragusa is assistant professor of political science at the College of Charleston and creator of the Rule 22 blog that can be found at