A few days before a federal commission was scheduled to decide the fate of Ellsworth Air Force Base, South Dakota’s two Senators preemptively released a lengthy statement pledging to work together on issues of importance to the state.

“We both strongly believe that the time for emphasizing partisan differences and partisan attacks is long over and that South Dakotans are eager that both of us work as closely together as possible, which we are committed to doing,” Sens. John Thune (R) and Tim Johnson (D) wrote in the Aug. 23 letter.

It was a striking public statement from two political enemies who had spent the better part of the past four years trying to end the other’s career. But the declaration came at a time when both Senators were bracing for the worst: the loss of a military base that is their state’s second largest employer.

Within 72 hours, they were saved from their greatest fear, as the Base Realignment and Closure Commission shunned the Pentagon’s recommendation to shutter Ellsworth and voted instead to keep the base open.

Now, the question is how long will the Thune-Johnson alliance remain intact, given that these two political rivals may be headed for yet another showdown in 2008.

Thune is the early frontrunner to lead the National Republican Senatorial Committee in the 2008 election cycle — the same year that Johnson will be seeking a third term. Johnson said he “anticipates” that Thune will be the chairman of the NRSC, and acknowledged “maybe this will come apart, but I hope not.”

“I think we have … come to terms with an understanding we will work together where we can,” Johnson said.

For Thune, the decision to keep Ellsworth open allows him to expand his political portfolio beyond South Dakota’s borders. The Republican Senator had campaigned in 2004 on the idea that, as a Republican in a GOP-controlled capital, he would be best positioned to keep the base open. That’s why the closing of Ellsworth, had it happened, would have been so damaging: It would have forced Thune to shore up support in his home state rather than advancing his national ambitions.

But by helping convince BRAC to keep the base open, Thune has instead added to his reputation of overcoming long odds to win. Less than a year earlier, Thune defeated Senate Minority Leader Tom Daschle (D-S.D.) in the most closely watched Senate race of 2004. His campaign victory earned him the title of “giant killer” for being the first challenger to defeat a Senate leader in more than half a century.

The Pentagon, which recommended that Ellsworth be closed, is Thune’s latest adversary to go down in defeat.

“He was extraordinarily effective in making the case about the impact of [closing Ellsworth] on his state,” said Senate Majority Whip Mitch McConnell (R-Ky.). “Typically, these BRAC recommendations are not adjusted in any major way, but I would call that a major adjustment. That was a great victory for him.”

Much to the chagrin of GOP officials, Thune suspended all campaign activity once it was announced in the spring that Ellsworth was being targeted for closure. He declined invitations to appear at Republican fundraisers across the country and even postponed a $100,000 event in New York City for his own political action committee.

The Ellsworth victory now allows Thune to spend part of his time helping the national Republican Party. He recently appeared at two fundraisers that raised about $200,000 for Sen. James Inhofe (R-Okla.). And the South Dakota Republican acknowledged that he is interested in chairing the NRSC in the 2008 election cycle.

“Some folks have talked to me about it, and I am at least entertaining the thought of possibly running for that,” Thune said in an interview last week. “It is early on right now, but I think the key is recruiting good candidates and then raising money, and those are two things I think I can do well.”

Democrats seized on Thune’s renewed willingness to spend part of his time criss-crossing the country to raise money for GOP candidates.

“It is clear his priority is not South Dakota,” charged Phil Singer, spokesman for the Democratic Senatorial Campaign Committee. “BRAC was not a big victory for him, but rather a big sigh of relief for him.”

But Republicans were quick to point out that whether Democrats like it or not, Thune has a national profile. Inhofe said many of the contributors that attended his fundraisers told him they had donated to Thune’s 2004 campaign.

“Almost everyone who came in, of course they were real heavy hitters for me, almost everyone of them had given to him,” Inhofe said. “So that gives you an idea of the national significance of his race and the national impression that is out there.”

Further evidence of Thune’s national appeal is the fact that his PAC raked in more than $500,000 in the first six months of this year.

McConnell, who is expected to succeed Senate Majority Leader Bill Frist (R-Tenn.) in the 110th Congress, said Thune has the qualities to be an effective leader of the NRSC.

“I think anyone who has won a tough race, you develop the kind of campaign skills that are very useful in a job like that,” said McConnell, himself a former two-term NRSC chairman. “He certainly demonstrated, I think, great political skill.”

Even though Thune is generally considered a loyal soldier for the GOP, Thune confidants said he is not afraid to use his political skills against his own party if it aids his own state. His allies note that when the White House refused to help Thune in his bid to keep Ellsworth open, the freshman Senator openly opposed President Bush’s nominee for U.N. ambassador, John Bolton, though Thune himself never made the linkage.

Thune said he holds no animosity toward the Bush administration, but added in an interview that he would not support the administration in the future on issues where their “mutual interests are not aligned.”

For now, Thune said he is evaluating each campaign fundraising request “on a case-by-case basis” to determine where he can be of the most assistance.

“I want to be helpful to the team and keep the majority in the Senate,” Thune said. “There are a number of colleagues running this time who are friends, and I will do as much heavy lifting as I can.”