As state and national Republicans await a definitive decision from Housing and Urban Development Secretary Mel Martinez (R), there is already evidence that his likely entry in the Florida Senate race could strain the sibling relationship between President Bush and Gov. Jeb Bush (R) down the road.

Still, it remains unclear what effect Martinez getting into the GOP fray — and the role the White House would then play — would have on reducing the size of the Republican line-up. Most observers believe it would take some time for the eventual primary field to settle.

“It’s kind of like every person for themselves right now,” said one GOP strategist, adding that Martinez would immediately start picking off money, organization and support from the other candidates if he was to enter the race. “Nothing’s really changed in terms of the strengths and weakness of the other candidates.”

While the White House and other national party leaders like National Republican Senatorial Committee Chairman George Allen (Va.) have made their desire to have Martinez in the race no secret, Jeb Bush made clear last week that he plans to stay neutral in the primary race even if Martinez runs.

“If he runs, he’s going to have to earn it,” Gov. Bush said of Martinez, according to a report in the St. Petersburg Times on Friday. “I certainly am not going to endorse a candidate in the primary, and the White House won’t either.”

In what was perceived as a swipe at the Washington-based jockeying to recruit Martinez, the governor also praised those “who had the courage to run when [Sen.] Bob Graham [D] was still in the race” in an article published Friday in the Palm Beach Post.

The leading Republicans currently in the Senate contest are former Rep. Bill McCollum, state House Speaker Johnnie Byrd and state Sen. Daniel Webster, although many GOP insiders view Martinez as the most attractive candidate because of his credentials as a moderate and ability to connect with the state’s Hispanic community.

On the Democratic side, former state Education Commissioner Betty Castor, Rep. Peter Deutsch and Miami-Dade Mayor Alex Penelas are competing for the party’s nomination.

After initially passing on the race in June, Martinez said last week he is “very, very seriously looking” at running to succeed Graham, who announced his retirement earlier this month. He is expected to announce his plans in the next few weeks.

Republicans in Washington generally do not believe that Martinez’s candidacy would immediately clear the GOP field. It is more likely that the field would thin in the first few months of next year, before the state’s filing deadline in early May.

“I don’t think you’ll see anyone get in and then all of a sudden two people get out,” the strategist said. “Nobody’s anticipating that.”

Meanwhile, Rep. Katherine Harris (R) is continuing to entertain the possibility of entering the race, regardless of what Martinez eventually does. Some observers believe the White House’s and, specifically, top Bush adviser Karl Rove’s, recently renewed effort to woo Martinez was based in part on a desire to thwart a Harris candidacy.

Harris, demonized by Democrats for her role as secretary of state during the 2000 Florida presidential recount, wants to conduct polling before making any decision about her political future.

“She needs empirical evidence to see whether or not she could win the Senate race, number one, and number two to see if she helps or hurts the president,” one knowledgeable source said. “No one knows for sure, and I think that needs to be tested.”

However, some insiders believe Harris could also be positioning herself to challenge Sen. Bill Nelson (D) in 2006, when he faces re-election for the first time. Nelson handily defeated McCollum in 2000.

In the meantime, though, the GOP candidates already in the 2004 race are scrambling to shore up their support and assess the impact a Martinez candidacy could have on their campaigns.

Webster, viewed as the favorite of Jeb Bush, has faced questions over whether he can raise the kind of money needed to stay competitive in the race, and Martinez’s entrance would surely further hinder his fundraising efforts.

Byrd, meanwhile, has had little trouble raising money, but his organization could be hurt by having the HUD secretary in the race.

McCollum, who won the party’s nomination in the 2000 Senate race and then lost the general election, has released polling that showed him leading the other GOP candidates. But his fundraising so far has been less than stellar for a self-described “frontrunner.”

His biggest obstacle, with or without Martinez in the race, is the view held by many state and national party activists that McCollum would be the weakest general election nominee.

As speculation grew last week that Martinez was close to joining them, all three campaigns sought to reaffirm their commitment to the race and their support within the GOP establishment.

McCollum sent out a flurry of news releases on Thursday, in an effort to show that supporters are still solidly behind his campaign. A joint statement from Florida GOP Reps. Mario Diaz-Balart and Lincoln Diaz-Balart directly addressed the former Congressman’s ties to the Hispanic community.

“He has been a leader in the fight for freedom and democracy in Cuba and we are proud to support him,” the statement said. “Bill McCollum is our strongest possible candidate for this Senate seat and it is time for all of us to unite behind his candidacy.”

But while the candidates vowed to stay in the race, another Republican said the situation would change quickly if the White House decides to publicly back Martinez in the primary.

“I think if the president or Karl Rove calls you, everybody gets out,” said one former Florida Republican operative.

Martinez had been courted by national Republicans to enter the race earlier this year, when Graham’s plans were still unclear. At the time Martinez resisted their overtures, appearing to be more focused on running to succeed Jeb Bush as governor in 2006.

Faced with the likely prospect of a bruising gubernatorial primary with at least two statewide officials, and following Graham’s Nov. 3 retirement announcement, Martinez began to reconsider the race, sources said.

“It’s apparent to Martinez I think that he would come into the governor’s race a few steps behind,” said the former GOP operative.

Martinez, 57, is the former chief executive of Orange County, winning election in 1998 with the support of Democratic voters. He is not well-known statewide, but he would enter the winner-take-all primary with an ideological advantage.

Like Rep. Mark Foley (R), a moderate Republican from South Florida who had been considered the frontrunner in the primary before he dropped his Senate bid in August, Martinez would likely be the only moderate in the race.