DeMint had long fancied himself a conservative kingmaker, meddling in many Republican primaries by means of his outside activist organization, the Senate Conservatives Fund. That had often set him at odds with GOP leadership, who viewed the SCF in the same way they might view the Club for Growth: a group devoted to making it harder for more electable Republicans to win their party's nomination.
But the fact that DeMint was himself Senator rankled his fellow members of Congress even more, to the point that he had to promise he would stop trying to unseat incumbents—a promise he apparently broke earlier this year when SCF transferred $500,000 to the Club at the precise moment they were (successfully) trying to nuke Dick Lugar in Indiana.
Now DeMint will have a much freer hand to interfere in GOP internal politics as it suits him, though Heritage is surely not immune to political pressure either. Still, it's easy to imagine how this kind of free agency would appeal to DeMint. And the job may appeal to his pocketbook as well: The outgoing chief of the Heritage Foundation earns a cool $1 million a year. That's quite the upgrade for DeMint, whose $40,000 net worth made him one of the least-wealthy members of Congress.
So what happens next? First, GOP Gov. Nikki Haley will appoint a temporary replacement. That person will serve until 2014, when a special election for the final two years of DeMint's term will be held, to coincide with the state's regularly-scheduled general election. Of course, there will be a ton of scrambling over that appointment, and whoever gets tapped could very well face a competitive primary. Haley could also name a caretaker who promises not to seek election, which would instigate an even wilder free-for-all.
It's also important to note that South Carolina's other Senate seat is also up for re-election in 2014. There'd already been a lot of chatter about a possible GOP primary challenge to Sen. Lindsey Graham, but now hopefuls will have to think about whether they want to go up a two-term senator (tougher) but for a six-year term (more rewarding), which is what a run against Graham would involve. If they go for DeMint seat, it would mean facing an appointee (easier) or perhaps an open seat (easiest of all) but for a two-year term (obviously less rewarding) which would then require them to run for a full six-year term just two years later (in 2016, when the seat would ordinarily be up).
Some observers think DeMint's move might save Graham's bacon because would-be senate candidates will find the former race more appealing than the latter, but that's no sure thing. And if a ton of big names start piling into the DeMint seat, other folks might opt for Graham as an easier route.
In the meantime, all eyes will be on Haley—and as we've seen in recent years, Senate succession drama can be intense indeed. (Just think about New York, Massachusetts, and Illinois, for instance. Hell, one governor wound up getting impeached as a direct result of the appointment mess!) The State suggests she could tap Rep. Tim Scott (SC-01), who just won a second term last month. Scott is apparently DeMint's preferred choice, and he'd become the only African American in the Senate. Other possibilities include Reps. Mick Mulvaney (SC-05) and Trey Gowdy (SC-04), who were also both first elected in 2010. (And if Haley taps a member of the House, that'll trigger another special election in turn.)
Other possibilities, according to the paper, include naming someone like former state AG Henry McMaster as a placeholder, or, even more intriguing, Haley resigning and having Lt. Gov. Glenn McConnell appoint her to the seat. The State makes that possibility sound unlikely, but Democrats may find themselves rooting for it, since governors who appoint themselves to the Senate have historically performed very poorly when seeking election. (Indeed, only one of the nine who've done this has subsequently won at the ballot box: Kentucky's Happy Chandler, in the early '40s.)
Needless to say, no matter how you slice it, this is some seriously major news—and as always, we'll be following further developments very closely indeed.
(P.S. One housekeeping note: From this point forward, we'll be referring to the Graham race as "SC-Sen-A" and the DeMint race as "SC-Sen-B.")
2:21 PM PT: Some South Carolina updates from later in the day on Thursday:
• The Atlantic's Molly Ball says an unnamed source tells her AG Henry McMaster is not interested in a caretaker appointment.
• A nameless South Carolina Republican tells TPM that Haley is considering Chad Walldorf as a possible placeholder. Walldorf is the founder of Sticky Fingers, a regional chain of barbecue restaurants.
• The Hotline's Reid Wilson runs through a long list of names of potential appointees, though all of these folks could also conceivably run in 2014 as well: state Rep. Nathan Ballentine (a Haley confidante), ex-Rep. Gresham Barrett (an establishment type who lost to Haley in the 2010 GOP primary, getting smoked in the runoff), Rep. Joe Wilson (of "you lie!") infamy), AG Alan Wilson (his son), David Wilkins (a major Republican fundraiser and Dubya's ambassador to Canada), former state party chair Katon Dawson, and Haley's deputy chief of staff Tedd Pitts.
• Dawson confirmed his interest to The Hill, and another Haley ally, state Rep. Ralph Norman, also says he'd like the job.
• Wilson adds that Rep. Tim Scott, supposedly DeMint's favorite, is apparently more interested in becoming governor some day. (Through a spokesman, DeMint denies pushing for anyone.) It's also worth noting that Scott was just named to a seat on the powerful Ways and Means Committee; last week, Arkansas Rep. Tim Griffin cited that very same thing as a reason why he won't run for Senate, so maybe that's on Scott's mind, too.