HEATING UP IN THE SUNSHINE STATE…. In January, when it looked Florida Gov. Charlie Crist would face former state House Speaker Marco Rubio in a Republican Senate primary, a poll showed the governor with a commanding lead, 57% to 4%.

This week, a Research 2000 poll conducted for Daily Kos showed things a little more competitive. Crist now leads Rubio 47% to 37%. A 10-point lead may seem reasonably strong, but the trend should cause some panic on the governor’s campaign — Crist is fading fast and Rubio has excited the right-wing base. This poll is consistent with other recent data pointing in the same direction.

Markos Moulitsas explained:

These trendlines are bleak for Crist, and there’s little chance of him surviving. Remember, Rubio hasn’t spent a dime on media yet. This is all grassroots driven, and the teabaggers are engaged, angry, and looking for the next Scozzafava. Crist is in their crosshairs, and the governor has been flopping all over the place hoping to stem this growing tide against him, and failing. Note — 50 percent of Republicans still don’t know who Rubio is. The more he raises his name ID, the better he does.

Chris Cillizza added, “That Rubio has made up so much ground without spending any real money on voter contact — television or radio ads, direct mail etc. — should be very worrisome to Crist as it seems to suggest considerable softness in his numbers. In other words, the more Republicans look closely at Crist, the less they like what they see.”

Markos also tested some hypothetical general election match-ups. If Crist manages to get the GOP nomination, he’ll still easily defeat the likely Democratic candidate, Rep. Kendrick Meek. Of course, Crist’s chances of winning the primary are growing increasingly remote. What if he runs as an independent against Rubio and Meek? The three-way contest is basically a toss-up.

But here’s a twist — if Crist becomes a Democrat, he’s in a stronger position. It prompted Markos to conclude that Crist’s “cleanest path to a Senate seat” is “switching parties and making an earnest transition on the issues.”

For the record, there hasn’t been so much as a hint from Crist about a willingness to switch. On the contrary, he’s spent the last several weeks trying in vain to convince Florida Republicans that he’s really more conservative than he seems (which, incidentally, is what Arlen Specter did before he realized it was a lost cause and became a Dem). For that matter, it’s not at all clear if Florida Democrats would accept Crist with open arms.

But it’s fun to ponder, I suppose.

Another angle to consider is what Florida Dems do with this changing landscape. When Crist announced he was running for the Senate, he was largely considered a shoo-in, and high-profile Dems who would have otherwise considered the race decided to take a pass. If Rubio seems likely to get the GOP nod, will the Democratic field grow with the changing circumstances?

Or are we dealing with a dynamic in which the best chance of a Democrat winning the race is for Crist to switch?

And if Crist can’t win the primary, and doesn’t want to become a Dem, does he really throw the state a curveball and decide he wants to be governor again after all?

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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.