South Carolinian Senator Jim DeMint, a leading Republican and founding member of the Senate Tea Party Caucus, announced his resignation Thursday, The Hill reported.
DeMint's decision to leave the Senate shocked Washington insiders, who have seen DeMint as a influential conservative leader in Congress.
DeMint is leaving to become president of The Heritage Foundation, a conservative research group.
"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," DeMint said in a statement.
His resignation comes as Tea Party members of Congress face fierce pressure to make compromises.
The job change will offer "substantial" financial benefits to DeMint. While his 2010 net worth was $65,000, among the lowest for Senate members, the current Heritage president earned over $1 million in 2010, according to the New York Times.
South Carolinian Governor Nikki Haley will now appoint a successor who will run to maintain the seat in a 2014 special election.