The Senate Conservatives Fund, the political action committee founded by retiring Sen. Jim DeMint R-SC) had a VERY MIXED record when backing Senate candidates.

Mandel Ngan / AFP - Getty Images file

Sen. Jim DeMint, R-SC, speaks during The Family Research Council (FRC) Action Values Voter Summit on Sept. 14, 2012 at a hotel in Washington, DC.

Related: DeMint will leave Senate to head Heritage Foundation

Out of the 20 candidates the organization gave money to, 15 won their primaries -- but just seven won the general election.

The winners included Marco Rubio, Rand Paul, and Ted Cruz.

The losers included Sharron Angle, Christine O'Donnell, Ken Buck, and Richard Mourdock.

Total candidates receiving funds from Senate Conservatives Fund: 20
Total who won primaries: 15
Total who won general election: 7

2010
Marlin Stutzman - IN - lost primary
Sharron Angle -- V -- won primary, lost general
Ken Buck -- CO -- won primary, lost general
Chuck Devore -- CA -- lost primary
Ron Johnson -- WI -- won primary, won general*
Ovide Lamontagne -- NH -- lost primary
Mike Lee -- UT -- won primary, won general*
Joe Miller -- AK -- won primary, lost general
O'Donnell -- DE -- won primary, lost general
Paul -- KY -- won primary, won general*
Raese -- WV -- won primary, lost general
Rossi -- WA -- won primary, lost general
Marco Rubio -- FL -- won primary, won general*
Pat Toomey -- PA -- won primary, won general*

2012
Ted Cruz -- TX -- won primary, won general*
Jeff Flake -- AZ -- won primary, won general*
Josh Mandel -- OH -- won primary, lost general
Richard Mourdock -- IN -- won primary, lost general
Mark Neumann -- WI -- lost primary
Don Stenberg -- NE -- lost primary

Updated 12:44 p.m. - South Carolina Sen. Jim DeMint, an influential Republican who has helped prod his party rightward, will step down from his seat in January to become the next director of the Heritage Foundation, a conservative think tank.

DeMint announced Thursday that he planned to succeed Ed Feulner, the longtime head of the Heritage Foundation, next month. The news of his departure was first reported by the Wall Street Journal.

"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. "No organization is better equipped to lead this fight and I believe my experience in public office as well as in the private sector as a business owner will help Heritage become even more effective in the years to come."

The Heritage Foundation said DeMint's "passion for rigorous research, his dedication to the principles of our nation’s founding, and his ability to translate policy ideas into action make him an ideal choice to lead Heritage to even greater success."

Since being elected to the Senate in 2004, DeMint has not-infrequently clashed with Republican leaders on specific pieces of legislation and the overall direction of the party.

His conservative obstinance made him a hero among the party's grassroots. DeMint wielded that influence through his Senate Conservatives Fund, supporting more ideologically pure candidates over candidates deemed more politically-able by Republican Party leaders.

DeMint had even been rumored in 2011 to be thinking of challenging Kentucky Sen. Mitch McConnell for the position of Republican leader, though he eventually declined.

Among DeMint's successes through his Senate Conservatives Fund was the championing of senators like Florida's Marco Rubio, Kentucky's Rand Paul, and Utah's Mike Lee. Among DeMint's failures were the two Senate candidates -- Richard Mourdock in Indiana and Todd Akin in Missouri -- who lost their 2012 bids in the wake of controversial remarks about rape.

"I think if you're interested in having Republicans control the Senate you have to back Republicans who fit their state and who can win in a general election not just in the primary," Maine Sen. Susan Collins, a moderate Republican, told NBC News about whether there were any lessons from DeMint's tenure on Capitol Hill.

J. Scott Applewhite / AP

Sen. Jim DeMint, R-S.C.

DeMint had said he would leave the Senate in 2016, following the completion of his second term, meaning his departure in January will be ahead of schedule.

South Carolina Gov. Nikki Haley, another conservative Republican who enjoys grassroots support, will be allowed to name a replacement, who would have to face a special election in 2014 to serve out the remaining two years of DeMint's term. A variety of Republicans could jockey to replace DeMint, from Haley herself to a couple of her allies -- Tedd Pitts, her deputy chief of staff, or State Rep. Nathan Ballentine -- to U.S. Rep. Tim Scott or other members of the state's GOP establishment.

"Looking forward, Governor Haley will now appoint a new Senator, and I know she will make the right choice both for South Carolina and the nation," Scott Said in a statement.

South Carolina Sen. Lindsey Graham, a relatively more moderate Republican who's expected to face a primary challenge, is also up for re-election that fall. 

There is also the broader question of who, among the 45 Senate Republicans, will seize the mantle of conservative leadership in the upper chamber. Several of the senators whom DeMint helped elect have modeled their actions after the Palmetto State senator, creating their own political action committees and breaking on occasion with the GOP leadership.

NBC's Tom Curry contributed.

Nati Harnik / Associated Press

Nebraska Sen. Deb Fischer applauds her supporters with her husband Bruce Fischer, left, at her election party May 15 in Lincoln, Neb.

Updated 11:20 p.m. — Insurgent Republican candidate Deb Fischer bested two rivals with superior financing and organizations to win the Republican Senate nomination in Nebraska on Tuesday. 

Fischer earned the right to face former Sen. Bob Kerrey in a Senate race seen as crucial to Republicans' chances of retaking the Senate next year. She and Kerrey will battle to succeed the retiring centrist Democratic Sen. Ben Nelson. 

Fischer bested her two Republican rivals, state Attorney General Jon Bruning and Don Stenberg, according to Associated Press projections. Bruning had enjoyed establishment support and had raised the most money, while Stenberg, who'd previously run for the Senate three times before, had worked to consolidate support from conservatives. 

A state senator who heads the Nebraska legislature's transportation committee, Fischer made a late charge for the nomination aided by a nearly yearlong fight between Bruning and Stenberg. 

Adding to that momentum was former Alaska Gov. Sarah Palin, who on Monday released a letter in support of Fischer.

Romney wins Nebraska primary

“We admire your conservative principles and know that you will not go to Washington to amass great wealth or power. You will go to Washington to serve the people of Nebraska, protect our Constitution and work for common sense solutions to help restore America,” wrote Palin, who made a habit of backing insurgent and Tea Party Senate candidates in 2010, often shortly before Election Day.

Fischer won't face a cakewalk on her way to Washington, though. Democrats tapped former Sen. Bob Kerrey, who served two terms representing Nebraska before becoming president of The New School in New York City, to succeed Nelson.

But Republicans are optimistic that they can paint Kerrey, a Vietnam War hero who unsuccessfully sought the Democratic presidential nomination in 1992, as an out-of-touch liberal. Kerrey, for instance, said last week that he also supports same-sex marriage in light of President Barack Obama’s similar pronouncement – a position that might not prove popular with Nebraskans come November.

Fischer has been the least well-funded of the candidates, and her small organization relative to her two primary challengers could prompt more assistance from the national Republican Party.

Moreover, were Fischer to become Republicans’ candidate, she would be facing statewide exposure for the first time, and against a seasoned political figure like Kerrey.

Republicans' chances of winning the Senate could be diminished, though, if they fail to win over Nebraska. While Democrats will play defense this fall in more Senate seats than the GOP, Republican candidates have struggled to catch fire in some states that had been previously seen as opportunities, narrowing the party's pathway to a majority.

While Fischer's victory would seem at first glance to fall along the fault lines in 2010 Senate primaries, which pitted less-experienced conservative insurgents against establishment-backed Republicans, the three-way primary in Nebraska made for a more complex breakdown in political loyalties. 

Bruning had raised the most money and developed the most extensive organization. Both Rick Santorum, the erstwhile presidential candidate and former Pennsylvania senator, and former Arkansas Gov. Mike Huckabee had endorsed Bruning, giving him particular heft among the state’s social conservatives.

Stenberg, who had hoping the fourth time was a charm in his bid to win a Senate seat, won the backing of Sen. Jim DeMint, R-S.C., a conservative kingmaker in primary races, along with the fiscally conservative Club for Growth.

Both Bruning and Stenberg had been fighting intensely in the GOP primary for much of the past year, aided in part by outside groups who have assisted each candidate.

South Carolina Sen. Jim DeMint (R-S.C.) said Thursday that Mitt Romney is beginning to look like the eventual Republican presidential nominee, and nudged Romney's rivals toward exiting the race.

DeMint, an influential conservative senator, met with Romney today on Capitol Hill; the former Massachusetts was in Washington today to wage a charm offensive with Republicans in Congress.

While DeMint hasn't endorsed a candidate, he gave Romney significant cover with conservatives -- a group with whom Romney has struggled occasionally during the primary season.

That extended to musing that the best thing for the Republican Party might be for Newt Gingrich and Rick Santorum to consider throwing their support to Romney.

"They can drag it out to the convention if they want," DeMint said of Romney's two main rivals, "but I think if some of them look at where they are, the best thing they could do was maybe look at kind of throwing their support behind the one who might be our nominee. Its beginning to look like Romney."

DeMint said he talks to Santorum over the phone, and emails Gingrich occasionally. Those two candidates have argued Romney isn't conservative enough to deserve the nomination, but DeMint, who endorsed Romney for president during the 2008 primary, said he never doubted Romney's credentials.

"I never really questioned his conservative credentials," DeMint said.

Conservative Sen. Jim DeMint stressed an unyielding agenda for Republicans during an opening speech Thursday at the annual Conservative Political Action Conference (CPAC).

DeMint, a South Carolina senator and conservative icon, cast aspersions toward the notions of compromising with Democrats during a time in which political strife has dominated Capitol Hill.

"We don’t have shared goals with the Democrats. The democrats can’t cut spending. Their whole platform is based on promising more from government," DeMint told activists gathered in Washington, D.C.

"Every time we compromise with Democrats, we spend more, we borrow more, we grow government," he said.

DeMint skewered the Obama administration in his speech, the first address as part of the three-day summit.

DeMint dealt mainly in broad strokes, outlining a “decentralized” approach to health care and transportation, DeMint argued for familiar themes to conservatives, including state’s rights and budget prudence.

One hot topic that came up – the Keystone pipeline, which DeMint said would ensure tens of thousands of jobs.

“Who could say no?  Folks, we’re not talking about complicated political philosophy here,” he said.

MYRTLE BEACH, S.C – Sen. Jim DeMint, the Tea Party favorite whose endorsement remains one of the most coveted in South Carolina (even though he insists he won’t get behind anyone), said today that he thinks that fragmentation in the electorate is not a bad thing.

Speaking to a group of reporters after a speech at the Tea Party Convention here, DeMint said that when he talks to Tea Party supporters across the state, “they’re supporting all of the candidates. They’re pretty divided and I think that’s a good thing because there are good things about all the candidates.”

When pressed on why he thinks division is a good idea, DeMint chuckled, saying, “In my Senate primary I got 22 percent.”

During his speech to about 150 Tea Party supporters here, DeMint praised, by name, all candidates – even a few who dropped out – except Mitt Romney, on whom he lavished praise earlier this week, and Rick Perry.

DeMint said South Carolinians wanted a candidate with “the courage of a Michele Bachmann or the simplicity of the proposals of Herman Cain. You look at Newt Gingrich’s great ideas and Santorum’s strong on social issues.”

He even praised Ron Paul, who has wide Tea Party support but whose views on foreign policy make him unacceptable to a large swath of the Republican electorate.

“Look at Ron Paul,” DeMint started. “If [Republicans] don’t listen to the problems of the unaccountable and out-of-control of the federal reserve, then our party is not going to be a governing majority.”

While he mentioned those candidates, he suggested he wouldn’t be picking one out of the group because depending on whom he supported, he might get pushback from all Tea Partiers who didn’t also like that candidate.

“I know there are probably a lot of folks in this room that feel strongly a lot of different ways and that’s why I am not involved,” he said as the audience laughed.