Sen. Jim DeMint abruptly announced plans to resign his South Carolina Senate seat to run the conservative Heritage Foundation...

Politico Contributor

Sen. Jim DeMint abruptly announced plans to resign his South Carolina Senate seat to run the conservative Heritage Foundation, a stunning move that could have repercussions in the chamber and in Senate GOP primaries across the country.

The tea party leader made the announcement that he'd replace Ed Feulner as president of the Heritage Foundation in January.

"It's been an honor to serve the people of South Carolina in United States Senate for the past eight years, but now it's time for me to pass the torch to someone else and take on a new role in the fight for America's future," he said in a statement.

(PHOTOS: Jim DeMint's career)

Senate Minority Leader Mitch McConnell said DeMint informed him of his decision to resign Thursday morning.

"We're sorry to see Jim go. He's had a distinguished career," McConnell told POLITICO in a brief interview. "My wife [Elaine Chao] is a distinguished fellow at The Heritage Foundation. She'll be reporting to him."

DeMint added in his statement: "I'm leaving the Senate now, but I'm not leaving the fight. I've decided to join The Heritage Foundation at a time when the conservative movement needs strong leadership in the battle of ideas. No organization is better equipped to lead this fight and I believe my experience in public office as well as in the private sector as a business owner will help Heritage become even more effective in the years to come."

DeMint also appears poised for a raise, with Feulner pulling in $1.03 million in 2010, according to public records. DeMint earned $174,000 in 2012 as a senator.

At Heritage headquarters blocks from the Capitol, dozens of staffers filed into a first-floor auditorium to hear the announcement and directly from DeMint, whose muffled voice could be heard emanating from the room. Several speeches were punctuated by laughter and applause.

The resignation is not expected to have an immediate impact on the balance of power in the Senate, where Democrats will hold a 10-seat majority next Congress. South Carolina Gov. Nikki Haley, a Republican, would appoint an interim senator until 2014, at which point a special election would be held.

DeMint had already planned to retire after his term ended in January 2017, but he gave no indications that he'd leave with more than four years left in his term. He previously served three terms in the House.

The senator has become an influential leader in the tea party, aggressively working in Senate primaries to prop up the most conservative candidates, and often becoming a thorn in the side of his party's leaders. While he gained prominence in 2007 helping to sink immigration reform supported by President George W. Bush, deriding such efforts as "amnesty," his profile grew enormously in the 2010 election cycle when he joined tea party forces to become an influential player in Senate Republican primaries. He often said he would prefer to see a Senate of 30 rock-ribbed conservatives, rather than 60 more moderate Republicans.

In the 2010 cycle, DeMint was an early supporter of Pat Toomey in Pennsylvania, whose candidacy effectively sent incumbent moderate Sen. Arlen Specter out of the Republican Party. And as his party was throwing its support behind Gov. Charlie Crist, the moderate Florida governor, DeMint was an enthusiastic backer of Marco Rubio, now a prospective 2016 presidential candidate.

"In eight years, he has personally led the effort to change the composition of the Senate for the better, and provided consistent and principled leadership in the fight for liberty and limited government," Toomey said in a statement. "He will be missed."

But DeMint's record in primaries was decidedly mixed. He gave late support to Christine O'Donnell in Delaware over the moderate Rep. Mike Castle, and O'Donnell's victory in the GOP primary ended up costing his party a seat in the 2010 midterms. He also backed Ken Buck, a Colorado Republican over the establishment favorite Jane Norton in the 2010 primary, but Buck lost to incumbent Sen. Michael Bennet.

DeMint has been unapologetic about his tactics, saying his party needs to return to its conservative roots in order to provide a contrast to voters, rather than caving on core party principles to move towards the Democratic positions. While those hard-nosed tactics have made him a rock-star with conservative voters, they have earned him no favors with party leaders and GOP senators who say he's hurt his party's ability to return to power in Washington, while booting his own profile in the process.

Alaska Sen. Lisa Murkowski, who won as a write-in candidate over Republican Joe Miller, was irked immediately after the 2010 elections when DeMint's political action committee -- the Senate Conservatives Fund -- fiercely attacked her in the general election. She blamed DeMint for costing her party the majority.

"I think some of the Republicans in the Congress feel pretty strongly that he and his actions potentially cost us the majority by encouraging candidates that ended up not being electable," Murkowski told POLITICO at the time.

In the 2012 cycle, there were fewer fights with his party leaders - namely because the National Republican Senatorial Committee decided to stay out of the primaries, for fear of engaging in the same intraparty warfare that cost their party the majority in 2010. He also said he would not target Republican incumbents. What resulted was a disastrous election cycle, where the party lost two additional seats.

With his decision to resign, DeMint now will play a crucial role with one of the country's most influential think tanks with Republicans on Capitol Hill.

"Jim DeMint has shown that principled conservatism remains a winning political philosophy," Thomas A. Saunders, Heritage's chairman of the board, told his employees Thursday morning. "His passion for rigorous research, his dedication to the principles of our nation's founding, and his ability to translate policy ideas into action make him an ideal choice to lead Heritage to even greater success."