(Image source: U.S. Senate ) BY CHRISTINA HARTMAN South Carolina Republican Senator Jim DeMint is stepping down from his seat in January — in news that stunned political observers Thursday. DeMint is a powerful conservative voice in the Senate and a darling of the Tea Party. DEMINT: “We’ve gotta figure out how to trim back and devolve the role of government.” DeMint will become the next president of The Heritage Foundation , a conservative DC think-tank. Though he had long acknowledged this would be his last term, he wasn’t expected to leave the Senate until 2016 when his term would have ended. In a statement Thursday DeMint said, “... the conservative movement needs strong leadership in the battle of ideas.” And he called The Heritage Foundation the “best equipped” to take on that fight. CNN’s Dana Bash speculates why he really left, suggesting he was sick of Congress after clashes with Republican leadership over party purity. BASH : “...a bit of a surprise... He is a purist. he's an anti-tax, anti-government purist. It does seem that he's kind of had it here.” So is this a case of better on the outside than the inside? Seems to be the theme among the chattering class. Per CNBC’s Rick Santelli : “Demint is the perfect guy to run the foundation. When we talk Tea Party there isn't a bona fide leader. ... Fiscal responsibility and I think Jim DeMint will bring that to the forefront...” But some aren’t as thrilled. Conservative columnist Byron York writes for The Washington Examiner: “DeMint’s departure is not only a blow to conservatives and Republicans. …  What about that commitment to the people of South Carolina?” As for those constituents, it’s up to South Carolina Governor Nikki Haley to appoint a successor. That successor will hold the seat until a special election in 2014. The choice is the governor’s, but CNN’s Peter Hamby says this is the man DeMint wants to take over — Republican Rep. Tim Scott. In a statement Heritage Foundation called DeMint a principled conservative with “dedication to the principles of our nation’s founding.”