Rubio Campaigns as Conservative's Conservative in Race Against Conservative Crist

Marco Rubio, the former Florida House speaker, must be feeling good.

He has closed a 30-point gap to challenge Florida Gov. Charlie Crist in the GOP primary polls for the U.S. Senate seat.

He's won the support of big-time conservative darlings like Rep Mike Pence of Indiana and anti-tax activist Grover Norquist. He is benefiting from the financial prowess of Sen. Jim DeMint, whose Senate Conservatives Fund on Monday launched a "money bomb" campaign to drop $200,000 in 24 hours on Rubio's primary campaign.

And he organized a cheeky photo-op Wednesday to mark the one-year anniversary of Crist's hug with President Obama to show the governor's support of the $787 billion stimulus fund that conservatives love to hate.

But he's not out of the woods yet.

Crist is still favorable to many on the right, having cut taxes in his state, wielded his line-item veto power and generally by comparing his actions to conservative hero Ronald Reagan. Crist's approval rating stands at 51 percent in recent polling, lower than it has been, but notably steady across party affiliation, making him an attractive general election candidate. Rubio and Crist are in a statistical dead heat in primary polling.

Crist, successor to wildly popular former Gov. Jeb Bush -- who's mum so far on his backing but whose ideological rift with Crist has been well played in the press -- also has a well-oiled machine behind him for the seat being held by placeholder and former Crist campaign manager, Sen. George LeMieux. LeMieux is one of dozens of GOP chieftains holding a fundraiser for the governor in Washington, D.C., on Feb. 22.

So the battle for the conservative label builds in Florida, as it has in several regions of the country where grassroots activists are pushing conservatives to challenge conservatives on the grounds they aren't conservative enough. Talk show host and former Arizona Rep. J.D. Hayworth has been developing a similar campaign in Arizona against 2008 GOP presidential candidate John McCain, while Gov. Rick Perry and Sen. Kay Bailey Hutchison duke it out in Texas over who wins the most conservative brand in the race for the GOP nomination for governor.

Rubio said the big-time endorsements that he's bagging now are "intellectually and ideologically based, not politically based."

Prominent GOP figures gave Crist endorsements early in the race because they thought he was going to win the race, Rubio said. But they are giving their endorsements to him now because "of what we believe, what we stand for."

"They don't take their endorsements lightly," he said.

But Crist campaign spokeswoman Amanda Henneberg, sister to Fox News reporter Molly Henneberg, said Rubio is "the consummate insider whose rhetoric on the campaign trail doesn't match his lengthy record."

"We are confident that by the end of this race, our good friends in Washington will better appreciate that there are enough pro-tax, soft on guns lobbyists already in Washington without Florida sending another," she said.

Tom Gaitens, the Florida field director for FreedomWorks, which has been spearheading Tea Party activities, said Rubio's credentials are more important than his establishment backers.

"We don't vet the supporters. We vet the candidates," he said.

But Everett Wilkinson, chairman of the South Florida Tea Party, told FoxNews.com that he thinks endorsements from Washington insiders, even those with conservative credentials like DeMint and Pence, will hurt Rubio's credibility "to some degree."

"You can't get big endorsements from D.C. without that happening," he said.

Wilkinson added that Rubio can overcome any potential image problems by continuing to appear at grassroots events.

"But if he keeps focusing on getting D.C. endorsements, that will bite him in the butt," he said.

Fox News' Stephen Clark contributed to this report.