By Kim Dixon and Thomas Ferraro
WASHINGTON (Reuters) - Republican Senator Jim DeMint, an independent-minded South Carolina conservative and a major voice of the Tea Party wing of the party, said on Thursday he will resign from the Senate in January to head the Heritage Foundation, an influential conservative think tank in Washington.
DeMint, often a thorn in the side of his own leadership in Congress, publicly criticized Republican House of Representatives Speaker John Boehner earlier this week for offering revenue increases in the bargaining with Democrats over the "fiscal cliff" of tax hikes and budget cuts set for the end of the year.
DeMint was in many ways ahead of his time in his arch-conservative views, which have become more in vogue with the rise of the fiscally conservative Tea Party movement in recent years. That movement suffered some losses though in last month's elections.
"I'm leaving the Senate now, but I'm not leaving the fight," DeMint, 61, said in a statement. "I've decided to join The Heritage Foundation at a time when the conservative movement needs strong leadership in the battle of ideas."
While his departure in January will remove a unique voice from the Senate, it likely will not affect the overall balance of power.
South Carolina is a solid Republican state, and South Carolina Republican Governor Nikki Haley will appoint a replacement through 2014, when a special election will be held.
Republicans had hoped to take control of the Senate in the November elections but wound up losing two seats, although two Tea Party favorites, Republicans Jeff Flake of Arizona and Ted Cruz of Texas, did win their races.
"The election mattered," said veteran Congress watcher Norm Ornstein of the conservative American Enterprise Institute. "It gave DeMint two more adherents in Flake and Cruz, but it is also clear that Republicans overall are moving in a problem-solving direction, not further to the intransigent right."
DeMint was elected in 1998 to the U.S. House. He won election to the Senate in 2004 and was re-elected in 2010. DeMint had vowed to limit himself to two terms in the Senate. His current term does not end until 2016, however, and he did not cite that as his reason for leaving.
MOVING HERITAGE RIGHT?
"It is surprising that a major political leader believes he can get more done working at a think tank than being a member of the U.S. Senate," said Darrell West, a scholar at the Brookings Institution who studies mass media and technology.
"DeMint seems to believe that focusing on long-term ideas outside elective office has greater potential than passing legislation. It is an extraordinary conclusion in many respects, but he may well be right," West said.
Ned Ryun, head of Tea Party group American Majority Action, said he hoped DeMint would move Heritage further to the right, criticizing the think tank for proposing several years ago an individual mandate for health insurance, an idea Democratic President Barack Obama included in his healthcare overall.
"Heritage has a robust presence and the resources to be a very prominent platform," Ryun said. "Would I love to have him in the Senate? Absolutely. But he said he was going to retire anyway."
Among the names circulated as potential replacements include South Carolina Representative Tim Scott, part of the wave of conservative freshmen elected to the House in 2010.
(Reporting By Kim Dixon and Thomas Ferraro; Editing by Fred Barbash and Eric Beech)
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