In a potential preview of what may become a more public fight between the duo for the 2008 Republican presidential nomination, Virginia Sen. George Allen has publicly questioned Senate Majority Leader Bill Frist’s (R-Tenn.) handling of three high-profile issues in recent weeks.

Allen was one of the leading voices in the call to invoke the so-called “nuclear,” or constitutional, option to eliminate filibusters on judicial nominees and has emerged as a critic of Frist’s approach to calling a vote.

In a trip to New Hampshire last weekend, more than a month after a compromise on judges had been reached, Allen said, “we should have gone for it earlier,” when asked about the timing of triggering the nuclear option.

The Virginia Senator has also been an aggressive advocate for John Bolton’s confirmation as U.S. ambassador to the United Nations, and was critical of Frist’s decision last week to bring the nomination to the floor without the votes required to end debate.

“Having played quarterback, I always like to have everyone in formation when you are ready to run a play,” Allen said of the Bolton vote on MSNBC last week.

Allen and Frist also tussled — at the staff level — over a resolution sponsored by the Virginia Senator apologizing to black Americans for the lack of Senate action on lynchings.

“What Allen is doing with Frist right now is akin to midget wrestling,” said an adviser to one of the other would-be Republican presidential candidates. “No one that matters for 2008 is paying attention to those kinds of barbs and comments.”

Allen partisans insist that his recent outspokenness has nothing to do with either Frist or a possible national campaign.

“Allen would be doing this whether he was talked about for president or not,” said one source familiar with the Senator’s thinking. “It fits into his persona. He is very frustrated by process.”

Despite those assertions, sources friendly to Frist and even many neutral observers believe more is at work in Allen’s comments, particularly given that the issues the Virginian has picked to champion are touchstones for social conservatives who will be critical in the 2008 nominating process.

“These may be the opening set of skirmishes over who is the right candidate for” social conservatives, said one well-connected Republican consultant. “Frist is competing for that vote very hard.”

Frist carried the banner for Christian conservatives earlier this year when he led the push to allow a federal court to re-examine the case of Terri Schiavo, a brain-damaged Florida woman who was eventually removed from a feeding tube and died.

Most observers break the Republican presidential primary field into three basic constituencies: moderates, mainstream/establishment GOPers and movement conservatives.

Both Allen and Frist seem to fit most naturally into the mainstream model — fiscally and socially conservative but with a streak of pragmatism that separates them from the party’s ideological warriors on the right.

But, to win the Republican presidential nomination Frist or Allen need to reach into the bloc of socially conservative voters who make up a near-decisive portion of the primary electorate.

Social conservatives’ “votes are obviously important to anyone who wants to compete in the mainstream conservative primary,” remarked one party strategist.

Privately, Frist allies reject the idea that the two men are politically similar and fighting for the same piece of the primary pie.

“George Allen is football analogies and chewing tobacco. That is an image he has carefully cultivated over the years,” said a source supportive of Frist. “Bill Frist is doctor and AIDS in Africa. One is a career politician and one is a citizen legislator.”

Allen served in the House and as Virginia governor before being elected to the Senate in 2000. Frist was a renowned transplant surgeon who had never held public office before defeating Sen. Jim Sasser (D-Tenn.) in 1994.

Publicly, the offices of Allen and Frist insist any talk of behind-the-scenes gamesmanship regarding 2008 is wildly premature.

“This had everything to do with Sen. Allen’s convictions and has nothing to do with politics,” said Allen’s chief of staff, Dick Wadhams, of his boss’s recent comments.

Amy Call, a spokeswoman for Frist, was complimentary, if less than effusive, about Allen.

“Sen. Frist and Sen. Allen, especially when he was in leadership, enjoyed a productive relationship and will continue to,” Call said.

But, in a potential presidential field that includes six Republican Senators — aside from Allen and Frist, Sam Brownback (Kan.), Chuck Hagel (Neb.), John McCain (Ariz.) and Rick Santorum (Pa.) are mentioned as potential candidates — each man is seeking to find an issue to ride to national attention. If it comes at the expense of another would-be nominee, so much the better.

One Republican consultant said that outside of McCain, former New York City Mayor Rudy Giuliani and former Rep. Newt Gingrich (R-Ga.), all the potential contenders are simply working at this point to become known nationally.

“They are just trying to present a favorable impression of themselves at the national level,” the source said. “The challenge for them is ‘How do I increase my name [identification] in a positive way.’”

Although neither man has had a particularly lengthy Senate career, the paths of Allen and Frist have crossed on more than one occasion.

Most notably, Allen was the first Senator to tell then-Majority Leader Trent Lott (R-Miss.) directly that he should step down in the wake of controversial comments praising South Carolina Sen. Strom Thurmond (R) in late 2002. Even as Lott struggled for his political life, Allen urged Frist to run for Majority Leader.

Earlier in the fall, Frist had backed Allen to replace him at the NRSC. That decision was made significantly easier because Allen was running unopposed for the post.

(Allen and Frist also share a background in athletics. Frist was the starting quarterback for his high school team; Allen, the son of the legendary professional football coach, played the same position at the University of Virginia.)

“They’ve never had a bad relationship,” said one source familiar with the interaction between the two men, a statement that subtly acknowledges Frist and Allen have also never been particularly close.

That tension has even begun to flow down to the staff level as was apparent in the recent back-and-forth between the two offices over the anti-lynching resolution, which Allen co-sponsored with Louisiana Sen. Mary Landrieu (D).

Frist refused to hold a roll call vote, noting that one of the sponsors had requested it be passed by unanimous consent.

Landrieu insisted that she had asked for a roll call vote — as did Allen.

In fact, Allen Press Secretary David Snepp took issue directly with Frist Communications Director Bob Stevenson’s assertion that Allen did not want a recorded vote on the matter.

“I don’t know why Bob Stevenson would characterize it that way,” Snepp told the Atlanta Journal-Constitution earlier this month, insisting that Allen would have preferred a roll call vote and had made that clear to his Senate colleagues.

According to Senate tradition, any Senator on the floor could have requested the yeas and nays on the bill, something Frist allies were quick to point out.