With Memorial Day having come and gone, the clock is ticking on New Mexico and national Republicans to commit to mounting a serious challenge to the state’s junior Senator, Jeff Bingaman (D), who is up for re-election in 2006.

Republicans have expressed an eagerness to capitalize on President Bush’s victory in New Mexico last November, which — while by a mere 6,000 votes — made the Land of Enchantment one of only two states that Bush picked up that had been in the Democratic column in 2000.

Bingaman’s seat is “definitely being looked at very seriously,” said NRSC spokesman Brian Nick. Citing Bush’s showing last November as part of a statewide trend, Nick said Bingaman’s voting record is “really out of touch with the state. And that kind of voting record would really make him ripe for defeat.”

At this point, though, nothing on the ground suggests that Republicans are ready to take on the four-term Democrat. According to sources on both sides of the aisle, as well as independent analysts, no one on the list of serious contenders has expressed any interest in running.

A candidate often mentioned as the most formidable would-be challenger is Rep. Heather Wilson (R), whose popularity in her swing Albuquerque-based district along with her moderate views on some social issues — which could play well even in liberal strongholds like Santa Fe — make her attractive to party insiders.

“She’s very popular, and she’s demonstrated an ability to be elected in a district that leans Democratic,” one Republican aide following the race closely said of Wilson.

Wilson remains mum on her intentions, and Democrats are already targeting her House seat for a possible pickup of their own.

The NRSC and the New Mexico Republican Party, though, say they are still talking to a number of candidates who they would like to see step up and run, including Wilson and Doña Ana County District Attorney Susana Martinez (R).

Martinez said Monday, however, that she is not interested in running against Bingaman, saying it would be difficult to unseat a popular sitting Senator who “has done a good job.” Martinez also denied speculation that she will run for state attorney general, although she admits to being courted for both positions.

“I thoroughly enjoy what I do, and I don’t see any reason to go do something else,” she said.

Rep. Steve Pearce (R-N.M.), who is also seen as a possible Senate contender, said he is intent on focusing on his House seat and committee assignments.

Marta Kramer, the executive director of the New Mexico Republican party, said that the only active GOP Senate candidate right now is Santa Fe City Councilor David Pfeffer. Pfeffer is a self-described “character” with a bushy mustache and pony tail, who recently grabbed local headlines by switching to the Republican Party with a speech blasting the Democratic platform and its leaders.

“There are certainly others we’d like to see run,” Kramer said.

A Pfeffer candidacy does not bode well for Republicans’ hopes of unseating Bingaman, said independent Albuquerque pollster Brian Sanderoff.

“The fact that Pfeffer is considering it shows that there are no highly visible Republicans at this time willing to enter the fray,” Sanderoff said.

Pfeffer “seems like a credible guy and seems to be willing to work hard,” Pearce said.

But the Congressman conceded that there’s not a lot of activity on the Senate front at this point even though Republicans have the impression that Bingaman’s record could bring him trouble.

Far from seeing Bingaman as vulnerable, Sanderoff describes the incumbent as “tough to beat.”

“If you did a poll today Bingaman would be up 25 points,” he said.

“The state bounces back and forth [politically] but it tends to stick with its incumbents,” Sanderoff said. “The only hope for the Republicans is that they recruit a quality candidate and fund him or her.”

Which, at this stage of the game, could pose a challenge. As of the March 31 filing date, Bingaman showed close to $600,000 in cash on hand, while Wilson had $180,000 and Pearce was just shy of $60,000.

Democrats, for their part, are not expressing any real concern.

“I don’t feel that [Bingaman is] vulnerable at all,” said one Democratic source with knowledge of the state’s politics. “He’s done nothing to give anyone an opening. And that’s one reason why [Wilson] and Pearce are hesitant to take him on even though they both clearly have statewide ambitions.”

Wilson and Pearce may both be waiting until 2008, when there may be an open Senate seat to pursue. Sen. Pete Domenici (R-N.M.) will then have to decide whether he wants to seek a seventh term, when he will be 76 years old.

But Republicans remain optimistic about their ability to find a contender against Bingaman who will attract national party attention and resources.

“I think that if a viable, credible candidate comes forward, why wouldn’t the RNC be interested? I’m sure they’ll take a look, and then, depending on their criteria, they’ll decide if they want to play,” Kramer said.