South Carolina Republican Senator Jim DeMint stunned Washington Thursday with the announcement that he will be stepping down next year to become president of the Heritage Foundation, a major conservative think tank.

For nearly eight years in the Senate, DeMint has been a bit of a troublemaker. He has opposed the major spending programs of both Presidents Barack Obama and George W Bush. On health care, he said no negotiations; let the unpopular bill be Obama's Waterloo. He similarly opposed the stimulus package while bucking his own party on the Wall Street bailout, the deficit-financed Medicare prescription drug benefit and No Child Left Behind.

Some of those last votes were cast while DeMint was still in the House. Shortly before the Medicare vote, DeMint recounted in a book that Bush looked at him and warned, "some of you have tough elections and we are watching how you vote." DeMint voted against the president and won his 2004 Senate race anyway.

DeMint was a reliable supporter of filibusters on liberal legislation – and likely a reason Senate Majority Leader Harry Reid has been talking about limiting the use of the filibuster in the next Congress.

In addition to being a troublemaker, DeMint was a kingmaker. He was active in Republican primaries, occasionally even endorsing challenges to his Senate colleagues – a break with precedent. His Senate Conservatives Fund not only helped finance conservative candidates, but also helped others identify which challengers were most viable. He frequently said he would rather have a Senate with 35 conservatives than a majority of moderates.

This irritated some Republicans in Washington, but made DeMint a hero to Tea Party activists throughout the country. He was an early supporter of Marco Rubio when the party establishment – and the early polls – were behind Charlie Crist in the Florida Senate race. He also broke with Senate Minority Leader Mitch McConnell to back Rand Paul when most party leaders in Kentucky, McConnell's home state, didn't.

Without DeMint, it is hard to imagine that Paul, Rubio, Wisconsin's Ron Johnson or Utah's Mike Lee would have ever made it to the Senate. The same is true for Senator-elect Ted Cruz from Texas. (Several of these men, by the way, are possible Republican presidential candidates.)

"Jim DeMint was the first person in Washington who believed in me – and invested in me," Rubio said in a speech after DeMint announced his departure.

The group formed a Tea Party, limited government caucus within the Senate Republican conference. Now DeMint will be heading a think tank that Republicans go to for ideas about policy. He says he thinks he may have more influence there than in the Senate. He may be right.

No think tank in the country is as close to GOP leaders as the Heritage Foundation. DeMint will have a chance to leave his mark in on it, and may also bolster Heritage Action, a 501c4 sister organization that is more expressly involved in political activism. The move is not without criticism. DeMint still had four years left on his Senate term, so some view this as unfair to the voters. Others argue that Heritage is already viewed as too partisan, and that being run by a politician rather than a scholar will further damage its reputation for reliable scholarship and policy analysis. Not to mention, with the move DeMint will go from being the fourth-poorest senator, to making a salary somewhere in the neighborhood of $1m per year.

But South Carolina already has a deep bench of DeMint-like Republicans waiting in the wings to claim the senate seat. (DeMint himself is said to be pushing Representative Tim Scott, a black Republican who defeated one of Strom Thurmond's sons in the GOP primary in 2010.) South Carolinians ought to be able to find comparable representation.

Second, think tank presidents are as involved in raising money and promoting their group's product as scholarship. DeMint is certainly qualified to perform those tasks. One point of interest will be whether DeMint ends up influencing the kind of policy work Heritage does. The senator has become more libertarian on certain issues in the past two years. (DeMint appeared in a video tribute to Ron Paul at the 2012 Republican National Convention, and has generally spoken well of the libertarian-leaning, antiwar congressman.) He voted to end the authorization of the Iraq war, supported amending the National Defense Authorization Act in order to protect jury trials for American citizens charged with terrorism and he has said that defense spending should be on the table when coming up with budget cuts.

Under Ed Feulner's 35 years of leadership, these were not the predominant views at Heritage. The think tank's foreign policy and defense experts have been reliably hawkish. Feulner himself has co-bylined op-eds with Weekly Standard editor William Kristol and American Enterprise Institute head Arthur Brooks arguing against defense cuts.

We know, however, where the new Tea Party think tank chief's loyalties still lie. In an interview about his job change – with Rush Limbaugh, no less – DeMint was asked if he was leaving because he was one of the conservatives allegedly purged by House Speaker John Boehner.

"It might actually work the other way around," DeMint said.