They don’t quite see themselves as gatekeepers to the Republican presidential nomination.

But a trio of GOP Senators from the early presidential nominating states of Iowa, New Hampshire and South Carolina made it clear Tuesday that they expect to play an influential role in the 2012 Republican primary contest.

Sen. Jim DeMint is planning an effort similar to the one he undertook in 2010, when he bucked the GOP establishment to visibly support conservative Senate candidates. DeMint said he intends to shape the primary beyond his home state of South Carolina.

“I plan to get involved before South Carolina because our candidates need to win in Iowa and New Hampshire as well as South Carolina — at least two of the three,” he said in an interview. “What I’m going to be trying to do around the country is to get the voters to think about the kind of person we want as president, before they think about who we want. What do we want them to believe? What are their values and principles? What are their priorities?”

DeMint expects to endorse a candidate before the Iowa caucuses, which kick off the quadrennial presidential nominating process, in an effort to exert maximum leverage. Last cycle, DeMint endorsed and raised money for nearly two dozen GOP Senate candidates running in competitive primaries, and while only a handful were elected, he garnered credibility among conservative activists for the effort. The South Carolina Republican said he planned to be similarly active in the presidential primaries.

DeMint said he has already fielded calls from some potential presidential candidates looking for advice on South Carolina and the policy priorities that they should focus on to appeal to GOP primary voters there. DeMint, who in 2008 endorsed former Massachusetts Gov. Mitt Romney, who plans to run again, said that he has no plans to run for president and that “it would take some kind of extraordinary event that I can’t imagine to get me in.”

Sen. Kelly Ayotte has yet to endorse in the broad field of potential candidates — and could remain neutral. But the New Hampshire Republican has left the door open to backing someone as the contest unfolds.

The freshman Senator won a hard-fought primary last year before cruising to victory in the November general election, and her backing in the crucial first-in-the-nation primary state could be attractive to presidential contenders.

Sarah Palin endorsed Ayotte in her Senate race, and the former Alaska governor and 2008 GOP vice presidential nominee is among the field of potential 2012 candidates.

Unlike DeMint, who is taking a broad, national approach to his participation in the primary, Ayotte appears to be limiting her focus to New Hampshire and protecting her home state’s importance in the nominating process. Still, Ayotte plans to meet personally with every Republican who joins the race. She has already fielded calls from a few potential candidates.

“My foremost role in the primary process in my view is to make sure that we preserve our primary because I think that New Hampshire plays a very important role,” Ayotte said. “But I also think that I plan on talking to all of the potential candidates — to talk with them about their viewpoints — and if I make a decision to endorse, I would do it based on what I think is best for our country.”

Sen. Chuck Grassley told Roll Call in a previous interview that he plans to endorse in the 2012 GOP presidential primary this summer, saying he is looking for a candidate who has the potential and the campaign resources to win primaries beyond the Hawkeye State.

But the Iowa Republican, re-elected to a sixth term in November, sought to downplay his effect on the caucuses, although he has spoken to three potential candidates thus far and plans on holding discussions with more in the coming months. Grassley did not endorse in the 2008 primary.

“You never know whether endorsing somebody or being for somebody or making a comment on somebody makes a big difference,” Grassley said. “I’m not a person to assume that I’ve got more power — unless I know I’ve got it. It’s pretty hard to measure.”

The Republican primary contest for the right to challenge President Barack Obama is getting started much later than the White House nomination fight in 2008. Several Republicans are considering a bid. But only a few are noticeably active in preparing, and even then only behind the scenes. Senate Republican Policy Committee Chairman John Thune (S.D.) plans to announce whether he will run by the end of February; other potential candidates are targeting the spring.

Sen. Lindsey Graham (R-S.C.) worked hard on behalf of Sen. John McCain (R-Ariz.) in the 2008 presidential primary, including in his home state. Graham said he would remain neutral this time around — at least initially.

Graham predicted the GOP presidential field would covet the endorsements of DeMint, newly elected Gov. Nikki Haley (R) and freshman Rep. Tim Scott (R) for the credibility that they could lend among conservative primary voters in South Carolina. But Graham emphasized that the true value of an endorsement is the political infrastructure that it brings to a campaign and how hard that network is worked by the endorsee and his backers.

“Here’s the thing I’ve learned about endorsements: It’s the organization that works the hardest that wins. I just didn’t endorse Sen. McCain, we worked ourselves to death for several years,” Graham said. “Public officials who work for you, who lend you their organization, who will go out and campaign for you are the most valuable commodities.”