I’ve been skeptical of the idea that Charlie Crist could pull a Joe Lieberman this year. But the latest Quinnipiac poll in the Florida Senate race shows Crist close to meeting one of the prerequisites for doing so: he’s within striking distance of becoming the de facto Democratic candidate, just as Lieberman was the de facto Republican candidate in Connecticut when he was reelected as an independent in 2006.

Crist narrowly leads with 37 percent of the vote while Republican Marco Rubio is at 32 percent and Democrat Jeff Greene at 17 percent. Kendrick Meek, the onetime Democratic frontrunner, would take just 13 percent. Crist’s lead is based on getting about half the independent vote, 40 percent of Democrats, and 20 percent of Republicans.

Lieberman had better numbers in just about every category. He won 54 percent of independents, 70 percent of Republicans, and held onto 33 percent of voters who identified with his old party. Here’s the key question: Do Florida Democrats basically concede the race to Crist the way Connecticut Republicans conceded to Lieberman? And whatever the party as a whole decides to do, will Jeff Greene or Kendrick Meek run as low-key a campaign as Republican Alan Schlesinger did in Connecticut?

Says Quinnipiac’s Peter Brown, “Gov. Charlie Crist’s small lead comes as neither Democrat breaks 20 percent in the trial heats. If that were to be the case in November, Gov. Crist would have a very good chance to win. But if the Democratic nominee can move into the mid-to-high 20s, Crist’s chances decrease substantially.”

Remember Arlen Specter — who I think Crist more closely resembles — didn’t lose his lead until very late in this year’s race.