The plight of Florida’s Charlie Crist – a Republican governor who apparently can’t win his own party’s Senate primary – underscores the divisions dogging an otherwise emboldened national GOP.

Races in all corners of the country raise the question of whether moderate candidates have a future in a party imposing ideological purity, and whether the GOP can attract moderate voters. In Senate races in Florida, Arizona, Utah, Kentucky and New Hampshire, conservatives backed by tea party activists are challenging more centrist candidates largely preferred by the party establishment in Washington.

Such bitter primaries are threatening the GOP’s fortunes even though, by nearly every other measure, the political winds are blowing against Democrats ahead of this fall’s midterm elections. And ramifications of the GOP family feud could extend beyond November, to the presidential election in 2012.

The Republican Party already is facing declining membership and a diminished geographic foothold as it has moved further to the right over the past few decades.

If the GOP ends up driving middle-of-the-road candidates from the party, how can it attract moderates and independents? Do those voters, already the most likely to be turned off by politics, simply stay home? Or do they turn out for independent candidates, making the two-party structure less relevant?

Neither result would be good for the Republicans. Still, party politics is hardly the only issue likely to sway votes in the fall. The economy is at the top of most voters’ lists. And the Democrats face their own nasty Senate primary in Arkansas, where moderate Sen. Blanche Lincoln is trying to fend off union-backed Lt. Gov. Bill Halter.

And in North Carolina, a labor group angry at moderate House Democrats over their health care votes has formed a third
party although they are struggling to get candidates on the ballot.

But those largely are isolated cases. The Republican moderate-conservative feuds have been fierce for quite a while, long before the emergence of the tea party movement. Last spring, moderate Sen. Arlen Specter bolted from the GOP as he faced a conservative challenge in Pennsylvania.

“I have found myself increasingly at odds with the Republican philosophy and more in line with the philosophy of the Democratic Party,” Specter said when he switched. Joe Sestak is opposing him for the Democratic nomination in the May 18 primary. No race epitomizes the GOP fracture more than the ugly Florida contest between Marco Rubio, the former state House speaker embraced by conservatives and tea party activists, and Crist, a moderate considered for the GOP presidential ticket in 2008.

Crist has dropped from favored Republican with a hefty lead in polls to GOP outcast with a double-digit deficit in a race that shows no signs of tightening. Polls suggest Crist could win as an independent in a three-way race. Rep. Kendrick Meek is the likely Democratic nominee.

Now Crist says he’s being “very, very thoughtful and deliberate” as he considers an independent run.

National Republicans are pressuring him to quit rather than run as an independent. Rep. Eric Cantor of Virginia, the second-ranking Republican in the House, said Tuesday: “Marco Rubio is just the type of leader our country needs.”

“The Republican Party, like the Democratic Party, goes through phases where it re-identifies itself and repositions itself somewhere on the conservative spectrum. Right now, this party is very conservative. And there’s good reasons for this party to be conservative,” said Sen. George LeMieux, R-Fla., Crist’s former chief of staff. LeMieux was appointed by Crist to fill the seat until a successor was chosen.

In other Republican Senate primary campaigns:

• Arizona Sen. John McCain, a four-term senator with an independent streak who was the GOP presidential nominee just two years ago, is in a tough primary battle against former Rep. J.D. Hayworth, a conservative talk-radio host embraced by tea party activists.

• Utah Sen. Robert Bennett, one of the most conservative members of Congress, is facing a serious challenge from his right, with his vote for President George W. Bush’s bank bailout drawing the wrath of conservatives.

• In Kentucky, outsider Rand Paul, the son of libertarian Rep. Ron Paul of Texas, is picking up endorsements and crucial support against Secretary of State Trey Grayson, causing consternation for the GOP establishment, especially Senate Republican Leader Mitch McConnell of Kentucky.

• Former New Hampshire Attorney General Kelly Ayotte, who national Republicans trumpeted as a top recruit, is trying to beat back challenges from conservative Ovide Lamontagne and another candidate, Bill Binnie.

Republicans succeeded when they backed a moderate in Massachusetts earlier this year as Scott Brown captured Sen. Edward M. Kennedy’s Senate seat.

But last November the intra-party split cost the GOP a House seat in New York that it had held for decades.

In New York’s 23rd congressional district, the nominee hand-picked by GOP leaders, Dede Scozzafava, dropped out of the race after a fierce challenge by conservative Doug Hoffman. Both remained on the ballot and split the Republican vote, which allowed Democrat Bill Owens to narrowly win the upstate New York seat Republicans had held for decades.

In a further blow to party orthodoxy, South Carolina Sen. Jim DeMint has started raising money and backing conservative Senate candidates running against the ones the National Republican Senatorial Committee wants. On Tuesday, DeMint endorsed Indiana state Sen. Marlin Stutzman even though the national GOP has persuaded former Sen. Dan Coats to run for the U.S. Senate there.

EDITOR’S NOTE: Liz Sidoti has covered national politics for The Associated Press since 2003.

Photo: Gov. Charlie Crist