Bombshell news out of Washington today: Jim DeMint is resigning from the U.S. Senate in order to run the Heritage Foundation, an influential conservative think tank.

Daniel Henninger broke the news on the Wall Street Journal’s website:

Mr. DeMint will leave his post as South Carolina’s junior senator in early January to take control of the Washington think tank, which has an annual budget of about $80 million. […]

In an interview preceding the succession announcement, Sen. DeMint said he is taking the Heritage job because he sees it as a vehicle to popularize conservative ideas in a way that connects with a broader public. “This is an urgent time,” the senator said, “because we saw in the last election we were not able to communicate conservative ideas that win elections.” Mr. DeMint, who was a market researcher before he entered politics, said he plans to take the Heritage Foundation’s traditional research plus that of think tanks at the state level and “translate those policy papers into real-life demonstrations of things that work.” He said, “We want to figure out what works at the local and state level” and give those models national attention.

Mr. DeMint, an active conservative partisan often at odds with his party’s leadership, says he will “protect the integrity of Heritage’s research and not politicize the policy component. Heritage is not just another grassroots political group.”

Still, the senator acknowledges that the political fires still burn: “This really gets my blood going again thinking about the possibilities. This is the time to elevate the conservative cause.”

More than most Senate Republicans, DeMint has left a long trail of wacky comments–like gays and unmarried women who are sexually active should not be classroom teachers. But he has become more influential than many far-right Republicans in Congress through his political action committee, the Senate Conservatives Fund. DeMint’s PAC has supported right-wing challengers to some GOP incumbents as well as conservative candidates in primaries for open seats or seats held by Democrats.

Some of DeMint’s favored candidates went on to win U.S. Senate seats, like Rand Paul (Kentucky), Marco Rubio (Florida), Pat Toomey (Pennsylvania), and Mike Lee (Utah). Other Republicans endorsed by the Senate Conservatives Fund went on to lose seats that the GOP should have won, like Christine O’Donnell (Delaware), Ken Buck (Colorado), Richard Mourdock (Indiana), and Todd Akin (Missouri). Technically, DeMint did not endorse Mourdock over longtime incumbent Richard Lugar before the GOP primary in Indiana, but he transferred campaign funds to the Club for Growth, which was running television ads against Lugar at the time. The Senate Conservatives Fund also backed Deb Fischer during the general election campaign in Nebraska this year, though it had supported a different candidate in the primary.

Outside the Senate, DeMint will have less direct influence over policy outcomes, like how Congress responds to the so-called “fiscal cliff.” (He was outraged by House Speaker John Boehner’s opening offer in negotiations with President Barack Obama.) The question is whether he will gain influence over public discourse as leader of the Heritage Foundation. Will more or fewer Congressional Republicans be afraid to land on his bad side now?

DeMint’s decision sets up a free-for-all in South Carolina in 2014. Governor Nikki Haley will appoint DeMint’s successor, and an election will be held in 2014 to serve out the remainder of DeMint’s term, which expires in 2016. Meanwhile, Governor Haley and South Carolina’s Senator Lindsey Graham are both up for re-election in 2014. Haley has lots of detractors within the South Carolina GOP, and Graham is considered a likely target for a primary challenger, because he is open to some compromises on tax and immigration policy.

According to CNN’s Peter Hamby, DeMint “has made it known in Columbia that he wants Tim Scott to be appointed to his seat.” Scott is the only African-American Republican in the U.S. House and would be the first black Republican U.S. senator to serve in decades. He would also be the first black senator from the South since 1881.

Alternatively, Haley may appoint herself to DeMint’s Senate seat, giving Scott a chance to run for governor in 2014. Other names floating around include former South Carolina Attorney General Henry McMaster, U.S. Representative Mick Mulvaney, and former South Carolina Republican Party chairman Katon Dawson, who was almost elected Republican National Committee Chairman in 2008.

Josh Kraushaar believes DeMint’s decision is “a HUGE boost to Lindsey Graham” because it will divert energy from a primary challenge to the special election. I suspect South Carolina has enough far-right conservatives to support a strong challenge to Graham in addition to a candidate to fill out the remainder of DeMint’s term. Having two Senate seats and the governor on the ballot in the same year could increase turnout for the Republican primary as well.

DECEMBER 17 UPDATE: Governor Haley appointed Tim Scott. He will be the first African-American senator from the South since Reconstruction.