Sen. Jim DeMint has been a gadfly in the Senate GOP Conference for years thanks to his crusade of enforcing a strict conservative orthodoxy on his colleagues.

But many of the South Carolinian’s fellow Republicans acknowledge that his decision this year to buck the party and endorse anti-establishment, tea party primary candidates may infuse him with considerable influence next year. But they’re divided on whether that’s a good thing.

Indeed, DeMint is on the cusp of being declared a kingmaker or a spoiler come Nov. 2, depending on how the ultra-conservative candidates he has boosted through his Senate Conservatives Fund fare in their general election contests.

“I’m into adding Republican Senators to the Senate,” National Republican Senatorial Committee Chairman John Cornyn (Texas) said. “And frankly, I don’t really care where they come from so much as I do the fact that we add to our numbers and add to our leverage and ability to direct the course of the country.”

However, DeMint’s colleagues fear that untested tea party candidates such as those in Nevada, Kentucky, Colorado and Delaware have actually made the Democrats more competitive in an election year when the majority would otherwise have a hard time competing against mainstream Republican candidates.

“Some of the stuff that Sen. DeMint’s for may go down swell in South Carolina; it may be wonderful there,” Sen. George Voinovich (R-Ohio) said. “But some of the stuff that he’s for or against may not be that well received in the state of Ohio. … The fact of the matter is a lot of this stuff is not that popular.”

Voinovich, who is retiring, added that DeMint’s hard-line approach may ultimately hurt the party’s shot at gaining power.

“If we’re going to maybe elect the next president as a Republican, if we’re going to move a lot of these things that people would like to see done, we have to have the majority,” he said.

Some in the party said DeMint’s use of his political action committee has been an attempt to shadow Cornyn, whose preferred candidates have been eliminated or scared away by DeMint picks in six races. Cornyn did not directly address the DeMint factor Wednesday, but he said he will take any win he can get in November.

[IMGCAP(1)]If DeMint’s candidates succeed, he’s likely to have more sway with those new colleagues than Senate Minority Leader Mitch McConnell (R-Ky.), Cornyn and other leaders because he was willing to back them before it was en vogue.

Even those critical of DeMint’s tactics and his all-or-nothing attitude acknowledge that his actions could have a significant impact, particularly on his colleagues up for re-election in 2012.

One veteran GOP operative said DeMint’s maneuvers, along with an influx of party purists, could force mainstream Republicans and moderates to pay attention to primary voters in a way they haven’t in years.

“He’s done most of them a favor in that they’re paying more attention to their constituents and paying more attention to their base,” the operative said.

DeMint has been careful not to criticize McConnell or any of his colleagues by name. But he makes clear that he sees his effort as a broader push to force fundamental changes on his caucus.

“What happens in our Conference is that we kind of come down to the lowest common denominator,” DeMint said. “I came [into the Senate] with 55 Senators, Republican Senators, a large majority in the House and a Republican in the White House. And what I hear all across the country is that we didn’t do what we said we were going to do.”

When asked why he backed candidates who were viewed as too conservative to win, DeMint argued that it’s key for the Conference not to “have a few who vote with the Obama agenda, [which] defines the whole Republican Party.”

He added, “We need people up here who understand we need to get back to limited government. We cannot afford to have other Republicans who don’t get that message.”

He also said the GOP made the right move by not embracing Sen. Arlen Specter, the Pennsylvanian who switched to the Democratic Party last year, and Florida Gov. Charlie Crist, who is running for a Senate seat as an Independent because it was clear he would lose a primary against former state Speaker Marco Rubio. (Specter lost his Democratic primary.)

“What we also need to realize is that Republicans would not have the wind at our back going into this election if we had stood up for candidates like Arlen Specter and Charlie Crist,” DeMint said.

DeMint’s endorsements of candidates have come at a variety of stages in the primary process. For instance, he announced his backing of former Rep. Pat Toomey (R-Pa.) early in 2009, just hours before Specter switched parties to avoid a primary battle with the conservative firebrand. Similarly, DeMint was an early supporter of Rubio and Ken Buck in Colorado, while he seemed to wait until some candidates such as Rand Paul in Kentucky and Christine O’Donnell in Delaware had gained steam before taking the endorsement leap.

In other instances, DeMint has held off formally supporting conservatives until after their primary wins — including Sharron Angle in Nevada, Joe Miller in Alaska and Mike Lee in Utah. He did not endorse Sen. John McCain or the Arizona Republican’s primary opponent this year, but DeMint has backed establishment candidates in Wisconsin and Washington. His candidates in California, New Hampshire and Indiana failed their primary bids.

Even though he has tried to avoid the appearance of opposing incumbent Senators, DeMint and his allies were involved, even if in an informal capacity, in at least one of those races. Several Republicans said operatives close to DeMint actively worked to help Lee best Sen. Bob Bennett at the Utah GOP convention. And DeMint himself publicly supported the upstart conservative.

“He has never hidden the fact that he liked Lee,” one Republican aide said. He “talked about Lee for months” before the primary.

One GOP Senator said DeMint’s actions could make it harder for the party to win seats but noted those defeats could end up being good for the party’s leaders in Washington.

“The more important issue is will these losses make our leadership wake up and realize what the real problem is,” this Senator said. “Jim senses what many of us do: that the American people are fed up with business as usual in Washington.”

However, one Senate GOP aide said McConnell, Cornyn and other Republicans backed more mainstream candidates because they had a better chance of winning in their general elections.

“When the stakes are as high as they are, how is purity somehow more sacred than the ability to stop the Obama agenda?” the aide said.

Of course, DeMint’s relationship with his leadership and much of his Conference has long been strained.

For instance, several years ago, DeMint forced a largely symbolic Saturday vote even though he knew he could not attend. Following the 2008 elections, he also suffered an embarrassing and crushing loss in his efforts to make sweeping changes to the GOP Conference’s rules during a closed-door caucus meeting.

Another Senate GOP aide suggested that what’s past may be prologue for DeMint next year.

“He’ll have some friends, sure. But he’ll have some enemies. … I don’t expect much to change for him,” the aide predicted.

David M. Drucker contributed to this report.