The unexpected retirement of Senator Jim DeMint, a conservative Republican from South Carolina who will vacate his seat to become head of the the Heritage Foundation, will create an unusual circumstance in which both of the state’s Senate seats are on the ballot in 2014.
A special election will be held to fill out the remaining two years of Mr. DeMint’s term, which was originally set to expire after the 2016 election. In addition, South Carolina’s other senator, the Republican Lindsey Graham, who was re-elected in 2008, will also be on the ballot in 2014.
Mr. DeMint’s retirement could conceivably help Mr. Graham, whose approval ratings in South Carolina are middling. Mr. Graham also draws the ire of some Republicans for being seen as too willing to compromise with Democrats, making him potentially vulnerable to a primary challenge.
If the stronger Republican candidates are drawn toward competing for Mr. DeMint’s former seat instead, Mr. Graham could be spared a difficult test. On the other hand, some of the candidates whom Gov. Nikki R. Haley might appoint to fill Mr. DeMint’s seat for the next two years, like Representative Tim Scott, are viewed as having bright political futures while being more reliably conservative than Mr. Graham, meaning that Mr. Graham could still be the more vulnerable target in a Republican primary.
Opportunities for Republicans to ascend to the Senate in South Carolina ought to yield competitive primaries because there is a large supply of well-qualified candidates.
All nine of South Carolina’s elected executive officials, from the governor, Ms. Haley, to the agriculture commissioner, Hugh Weathers, are Republicans. In addition, six of the seven representatives that South Carolina will send to the United States House in January are Republicans; the exception is the Democrat James E. Clyburn, who represents South Carolina’s majority-black Sixth Congressional District.
The abundance of Republican elected officials in South Carolina precludes Democrats from having much of a “bench” in the state — and may prevent them from making a strong run at either Senate seat in 2014.
The statistical models that FiveThirtyEight uses to forecast Senate and gubernatorial races include, among other factors, a variable to designate a candidate’s credentials, which is based on the highest office that he or she has been elected to. The more prominent the races that the candidate has won, the better he or she tends to do when running for the Senate or for governor.
We divide the offices into three tiers, which might be thought of as tantamount to professional baseball’s system of major and minor leagues.
In the top tier are candidates who have already done the equivalent of ascend to the majors by having been elected to a United States Senate seat or a governorship at some point. But these candidates are hard to find unless they are already the incumbents in those races. (An exception is when a governor crosses over to run for the Senate, or vice versa.)
So in practice, parties draw more heavily from the second tier of elected officials, which provide them with their top prospects when they want to compete for a Senate or gubernatorial seat. In this group are United States representatives and statewide elected officials, like attorneys general and secretaries of state.
Because almost none of these officeholders have been Democrats in South Carolina, the party has had to draw from the third tier of candidates, which consists largely of state senators and state representatives. These candidates face a far bigger transition when trying to compete for a major elected office like United States Senate or governor, in terms of raising funds, building name recognition and developing platforms that allow them to appeal to enough voters to win statewide.
And in some cases in South Carolina, Democrats have nominated candidates who have not held elected office at all. In 2010, their candidate for the United States Senate was Alvin Greene, an Army veteran who had never run for public office and who was unemployed when he was chosen as the nominee.
It is not mere happenstance that Democrats have had trouble fielding competitive candidates for statewide elections in South Carolina. Much of it has to do with the demographics and the geography of the state.
President Obama won 44 percent of the vote in South Carolina this November, more than he did in 19 other states. However, in South Carolina, it can be exceedingly difficult for a Democrat to go from winning 44 or 46 percent of the vote to 50 percent.
This is because of a concept we call elasticity, which is related to the number of swing voters in each state who might consider voting for either party.
Some red states like Alaska are also fairly elastic, meaning they have their fair share of voters who are political independents or who have moderate or mixed political views. Democrats usually lose in these states — but they can compete with the right candidates and under the right circumstances.
In South Carolina and some other states in the Deep South, however, there are very few swing voters. African-Americans vote for Democrats in overwhelming numbers, while the vast majority of whites are conservative and vote Republican.
This makes the outcome of elections in these states much more predictable. Democrats have a high floor for how many votes they receive, but also a low ceiling, and they almost always wind up coming up short of 50 percent.
Democrats’ problems are compounded in South Carolina because of the geographical distribution of black voters, who are heavily concentrated in certain cities, counties and Congressional and legislative districts.
This year, Mr. Clyburn, the Democrat, won overwhelmingly in South Carolina’s Sixth Congressional District, taking 94 percent of the vote and facing no Republican opposition. But Democrats lost the other six United States House races, and their candidates won no more than 45 percent of the vote in any of them.
This does not just make it difficult for Democrats to win elections in South Carolina. When they do, it is often in overwhelmingly Democratic districts. The candidates may have little practice in appealing to a broader constituency of voters, and they may accumulate liberal voting records that make them unacceptable to the few moderates in South Carolina.
Instead, the closest thing South Carolina has to a crossover candidate may be Mr. Scott, who won re-election this year in the First Congressional District. He is African-American — and Republican.