By Alexander Bolton - 12/06/12 05:49 PM EST
Sen. Jim DeMint (R-S.C.), a leading Senate conservative and founding member of the Senate Tea Party Caucus, will resign from office in January to become president of The Heritage Foundation.
DeMint, who frequently clashed with the Senate Republican leadership during his career over taxes, spending and political tactics, said he will continue to push his conservative vision from outside Congress.
DeMint's decision to leave the Senate after only eight years shocked Washington. DeMint had been seen as a future Senate leader for his party and was already a leader to a growing number of conservatives in the House and Senate.
At the Heritage Foundation, the senator will take over from Ed Feulner, who will become the group's chancellor. He also will be in line for a significant raise.
Feulner earned more than $1 million in compensation in 2010, according to Heritage's tax form for that year. DeMint's annual salary as a senator is $174,000.
DeMint is also not one of the richest members of Congress. On his 2011 financial disclosure report, DeMint only listed two assets, both IRAs, that are worth at least $1,000 each. He also received a book advance for his tome Now or Never last year of more than $43,000.
But DeMint also reported liabilities for 2011 that totaled at least $350,000 for two residential mortgages.
South Carolina Gov. Nikki Haley (R), who praised DeMint as a leader of the national conservative movement, will select a replacement to fill DeMint’s seat until a special election in 2014.
Haley said DeMint's voice "for freedom and limited government has been a true inspiration."
"On a personal level, I value Jim’s leadership and friendship," she said. "Our state’s loss is the Heritage Foundation’s gain."
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DeMint had previously announced that he would retire from the Senate when his second term expired at the end of 2016.
Chad Connelly, chairman of the South Carolina GOP, told The Hill that he was caught off-guard by the Senator's sudden resignation.
"This was a shocker. He's just been a conservative rock star for us for so long, and such a great leader," he said.
Connelly added that his exit is "going to open up a real ripple effect and we'll see a lot of candidates coming out" for the seat.
DeMint stepped down as chairman of the Senate Republican Steering Committee, a conservative policy discussion group, earlier this year, turning the reins over to Sen. Pat Toomey (R-Pa.). DeMint left that post in September after holding it since 2006.
During his Senate career, DeMint has repeatedly clashed with Democrats and also the leaders of his own party in his quest to reduce taxes and government spending.
Just this week, he criticized Speaker John Boehner's (R-Ohio) proposal in fiscal talks with the White House. DeMint said Boehner's proposal to include $800 billion in new tax revenues would "destroy American jobs and allow politicians in Washington to spend even more, while not reducing our $16 trillion debt by a single penny."
DeMint added that the best way to avoid upcoming "fiscal cliff" spending cuts and tax increases would be to extend the Bush-era tax rates for all income levels.
"[I]f neither party leadership is going to put forward a serious plan to balance the budget and pay down the debt, we should end this charade," DeMint said. "We can stop the fiscal cliff with the bill that House Republicans already passed that simply extends the current tax rates and replaces the defense cuts with reductions in wasteful spending.”
DeMint has been a vocal advocate for passing a balanced-budget amendment to the Constitution and holding repeated votes on repealing the 2010 Affordable Care Act.
He has also competed with the Republican leadership over political strategy. DeMint split with the leaders in 2010 to support Sens. Marco Rubio (R-Fla.) and Rand Paul (R-Ky.) over the establishment-favored candidates in Republican primaries.
DeMint also raised millions of dollars through the Senate Conservatives Fund, which he founded, to support candidates such as Sens.-elect Ted Cruz (R-Texas) and Jeff Flake (R-Ariz.).
He famously said that he would rather serve in the minority in a small, ideologically conservative Senate Republican caucus than in the majority with a large group of centrist Republicans.
“I'd rather have 30 Marco Rubios in the Senate than 60 Arlen Specters," he said in 2010, referring to the late Sen. Arlen Specter (Pa.), who in 2009 left the Republican Party to become a Democrat.
DeMint had been in line to become the ranking member of the powerful Energy and Commerce Committee in the next Senate, leading to speculation that he would adopt a more conciliatory approach to try and build a reputation as a legislative dealmaker.
DeMint told The Wall Street Journal that he is joining Heritage to expand the conservative movement.
"This is an urgent time," DeMint said. He added that in the 2012 election Republicans "were not able to communicate conservative ideas that win elections."
— Daniel Strauss and Alexandra Jaffe contributed to this story.
— Posted at 10:32 a.m. and last updated at 12:49 p.m.