THE SHIFTING FLORIDA WINDS…. I continue to think the Crist-Rubio contest in Florida is not only fascinating, but has far broader implications for the national landscape. The Republicans’ Senate primary — pitting Gov. Charlie Crist against former state House Speaker Marco Rubio — has become something of a proxy for the larger fight within the GOP, and the outcome will send a signal about the GOP’s near-term future.

Crist, thought not too long ago to be invincible, is now struggling so badly, the chances of him dropping his Republican bid to run as an independent appear to be growing.

When Marco Rubio announced Wednesday that he had raised a whopping $3.6 million over the past 90 days, it was another game-changer in the Republican U.S. Senate primary.

This just a day after Gov. Charlie Crist bucked fellow Republicans and vetoed an elections bill he was expected to sign — and the same day he reversed course and hinted he might veto a teacher tenure bill favored by Jeb Bush and other Republican leaders. On top of that, Crist plans to call the Legislature into special session this summer to overhaul state ethics laws — an issue Republican leadership has avoided this year.

It all fed a surge in speculation that Crist is positioning himself to drop out of the Republican primary and run instead as an independent.

“I tended to think, ‘he isn’t going to run as an independent.’ But with every passing day, I become more convinced he’ll run as an independent,” said Republican consultant David Johnson of Tallahassee.

When the subject of Crist running outside the GOP comes up, the governor and his team tend to dismiss it, often angrily, as if the scuttlebutt were somehow insulting.

When asked about the prospects of an independent bid yesterday, Crist said, “I’m focused on the session. I’m focused on these bills that are pending and coming up shortly. That’s where my focus is, there will be time for other things later.”

That’s not a “no.” It’s not even close to a “no.”

At this point, Crist is trailing in every metric. Campaigns can be unpredictable, but it’s hard to imagine the scenario in which Crist recovers and wins this primary. If he wants to hold elected office in January, Crist is probably going to have to consider alternative plans — and he has until April 30 (three weeks from tomorrow) to make an independent move. If he stays in the GOP primary beyond that date, he’ll take on Crist in the Aug. 24 primary, and likely lose.

As has become clear, the dominant right-wing element of the Republican Party has a point it hopes to make, and it has every intention of crushing Crist to send a message to other GOP candidates who may stray from the far-right line. The larger national significance is obvious: Republicans have decided that relative moderates no longer have a place in the party.

The party drove Arlen Specter away. The party drove Dede Scozzafava away. Now it has Charlie Crist in its proverbial crosshairs. Indeed, late last year, CNN’s Erick Erickson said on his blog that the special election in New York’s 23rd was “our Lexington,” while the Senate primary in Florida will be “Concord.”

No one would be in a better position to say, “I didn’t leave my party; my party left me” than Charlie Crist.

Update: And the very second I hit “publish,” I see that Crist has once again denied his interest in running as an independent. We’ll see.

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Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.