Six months into his tenure as the Senate’s top Republican, Minority Leader Mitch McConnell (Ky.) finds himself torn between competing factions of his Conference, as his stalwart conservatives pull out all the stops to thwart the Democratic majority while many of his rank-and-file grow increasingly frustrated with the lack of bipartisan legislative accomplishments.

Republicans have largely been content to follow McConnell and the conservatives’ lead in slowing down or blocking much of the Democrats’ agenda. But the ongoing debate over immigration reform has forced McConnell into a delicate position as he tries to balance pressure to move forward from Republican bill backers against conservatives’ demands that the Conference support their right to offer “poison pill” amendments.

“This is his most difficult challenge in getting a consensus in our Conference, there’s no doubt about that,” Sen. Lamar Alexander (R-Tenn.) said last week.

“It’s been pretty dicey,” agreed Sen. Jeff Sessions (R-Ala.), who, along with conservative GOP Sens. Jim DeMint (S.C.), Tom Coburn (Okla.) and others, have led the resistance to the bipartisan immigration bill as well as opposition to much of the rest of the Democrats’ legislative schedule.

The immigration debate may be just the first of many tough spots the new leader will find himself in as the summer wears on. Already, McConnell has found himself marginally at odds with Senate Energy and Natural Resources ranking member Pete Domenici (R-N.M.) and other Republicans who support the energy bill currently on the Senate floor. McConnell has held press conferences criticizing the measure.

And in July, internecine battles over appropriations may be particularly pitched as many Republicans look to defend funding for their pet projects while conservatives rail against what they see as Democratic overspending and egregious earmarks.

So far McConnell has been able to keep his Conference together on procedural votes that have tended to slow down the pace of legislation by waving the “minority rights” banner — an argument that Republicans said has been made easier by what they contend are Senate Majority Leader Harry Reid’s (D-Nev.) heavy-handed tactics in trying to push bills through the chamber.

Additionally, McConnell appears to have done little to dissuade small factions of Republicans from objecting to Democratic efforts to bring up bills that enjoy bipartisan support. Though it has been rare in previous Congresses, Reid has had to use time-consuming procedural maneuvers to win approval for proceeding to nearly half the bills Democrats have sought to bring up, even though only a handful of Republicans have voted against them.

“We haven’t felt like we’ve had input in the development of those bills, so the leader wasn’t about to use his influence to try to rein in conservative Senators,” said one Senate GOP leadership aide, adding that McConnell “could twist arms a little more than he has, but it’s questionable whether that would even work.”

Still, Democrats complain that McConnell hasn’t been forceful enough with his Conference, particularly with his right flank.

“When we were in the minority, if there were only four or five people who objected to going to a bill, Sen. Reid wouldn’t sacrifice the entire legislative process just for a few people,” said one Senate Democratic leadership aide. “Sen. McConnell on some of these issues needs to decide whether he wants to govern in a bipartisan manner or cater to the extreme right wing of his party.”

Though McConnell and most Republicans supported conservative efforts to block the end of debate on the immigration bill on June 7, McConnell still joined many others in his Conference in seeking to forge a deal with Reid to save the legislation from filibuster.

The deal to bring the bill back up, which was announced last week, would effectively shut out the most vocal conservative opponents. And it was a decision conservatives warned McConnell against making, citing the potential loss of unity the Conference has had so far.

“From a leadership perspective, we need to be careful about compromising the rights of our Senators to offer amendments,” Senate Republican Conference Vice Chairman John Cornyn (Texas), one of the few in the GOP leadership who vigorously opposed the immigration bill, said before the new deal was announced last week. “This is not the only bill we’re going to be considering, and if there’s no solidarity on the principle of protecting Senators’ right for amendments and a vote, then I think it’s going to be harder to hold people together in the future.”

Sessions said he urged McConnell to stand firm against attempts to bring the immigration bill back up.

“Sen. McConnell represents the face of the Republicans in the Senate, and he should take actions that insist on both our values and our constituencies,” Sessions said before the Reid-McConnell agreement was announced Thursday. “I would say to Mitch right now, ‘I see no need to bring this bill back up again. It can only hurt Members.’”

Though the new immigration deal will allow roughly 11 more votes on GOP amendments, those that DeMint and Sessions sought did not make the cut, primarily because they have continued to threaten to use time-consuming procedural tools to block the measure from becoming law. A DeMint aide on Friday said the South Carolinian would also object to the bill being sent to any House-Senate conference committee. (See related story, p. 3.)

McConnell spokesman Don Stewart said McConnell has only sought to ensure that all GOP rights are recognized during the immigration debate and that he has endeavored to not take sides.

“His side on this has been the Conference’s, not necessarily the final outcome,” said Stewart, who added that McConnell’s efforts on the bill have ensured that more Republicans will get votes on their amendments and that, in the end, the measure will have been debated on the Senate floor for more than three weeks.

Plus, Stewart said McConnell has not promised Reid that he can even help Democrats get the 60 votes needed to overcome a filibuster.

“He’s finding a compromise within the Republican Party,” added a second Senate GOP leadership aide. “He’s being a leader on this issue, and that’s not always going to make everybody happy.”

Another Senate GOP aide said it remains to be seen whether McConnell’s decision to disregard the objections of his conservatives on immigration will have any lasting effect.

“Is this going to blow through the bottom of the boat? I guess it depends on what the final product is and how hard they push,” said the aide.

But Alexander said McConnell is striking the right balance.

“In general, we need to let the majority know we expect, on any major issue, to have free and open debate and a good number of amendments,” he said. “But at some point, the leadership has to bring a bill to a vote, whether that’s [Supreme Court nominees] or immigration or an appropriations bill.”

Indeed, the next big test could come on the annual spending bills. Although Republicans allowed Democrats to easily pass spending bills left over from the past Congress along with a supplemental war funding measure, conservatives have been vowing to gum up the works on fiscal 2008 appropriations, which are scheduled to hit the floor in July.

On that issue, aides said, McConnell is likely to again attempt to balance the interests of conservatives and the regular rank and file.

“The conservatives realize you can’t block all of them. Some of the defense-related ones fall into that category,” said the second Senate GOP leadership aide. “But on others, I think [McConnell will] say, ‘Let’s address those issues.’”

Still, Democrats are hoping McConnell will show more of the arm-twisting he displayed in fashioning the deal on immigration when it comes to the spending bills — or they’re predicting that Congress might not be able to adjourn in time for Thanksgiving.

“If Republicans continue to stall and slow-walk and obstruct the way they have over the past six months, it’s going to be a long fall,” said the Senate Democratic leadership aide.

With the immigration debate continuing to unfold, most Republicans, including conservatives, still say they are happy with McConnell’s leadership style.

“I think Sen. McConnell has done a great job of managing [the Conference], and nothing has gotten to the president’s desk except minimum wage,” DeMint said.

Alexander said McConnell has been adept at managing the conservatives’ desires along with those of the rest of the Conference.

“The conservative base in our caucus is the anchor of our caucus, and most leaders use it to their benefit,” Alexander said. “Sometimes it’s to the disadvantage of the leader. … Mitch has [dealt with] both so far, which is what a good leader would do.”