HOW CRIST FOUND HIMSELF IN THIS MESS…. This is bound to be an interesting week for Florida Gov. Charlie Crist (R-for now). If he’s going to drop out of the Republican Senate primary and run as an independent, Crist has until noon on Friday (April 30) to announce his decision. The governor’s third-party bid seems to be a “foregone conclusion” in GOP circles, but there’s been no announcement about when the public can expect to hear about Crist’s plans.

But while the political world waits, it’s worth taking a moment to ponder how, exactly, Charlie Crist reached this point.

In 2006, a strong year for Democrats, Crist cruised to an easy seven-point victory in Florida’s gubernatorial election. By 2008, despite the GOP’s plunging popularity, Crist had sky-high approval ratings — including surprisingly strong support from Dems and independents. He was considered for McCain’s presidential ticket, was a shoo-in for the Senate, and it was widely assumed that it was only a matter of time before Crist was a tough-to-beat Republican candidate for national office.

And while it seemed impossible to predict a year ago, Crist is now likely to give up on the party he’s always belonged to. What happened? Adam Smith and Steve Bousquet had a terrific report over the weekend. It’s worth reading in its entirety, but of particular interest was the description of Crist embracing the mantle of post-partisanship.

The roots of Crist’s demise as a Republican superstar sprouted almost as soon as he took office. He revoked nearly 300 appointments by predecessor Jeb Bush, hailed Al Gore and teachers union leaders, and embraced Democrats’ calls to mandate paper trails for voting machines.

Crist wrapped himself in the glow of postpartisanship. After the drubbing Republicans took in 2006, Crist became the national model for successful Republicans, the ultimate bipartisan consensus-seeker. […]

The man who used to call himself a “Jeb Bush Republican” was thrilled when Democratic lawmakers called him one of the best Democratic governors Florida had ever had. He proudly showed off the note from former President Bill Clinton congratulating him for easing restrictions on ex-felons regaining their civil rights.

Republicans were willing to tolerate Crist’s occasional heresies because they didn’t necessarily think they had a choice — their GOP governor was a rising star, a popular Republican in a key state at a time when the party was faltering, and party leaders weren’t inclined to attack one of their own.

It apparently took a while for the Republican base to shake off that tolerance for Crist’s relative moderation when they realized his far-right primary challenger actually stood a chance at winning.

Worse, it took even longer for Crist to realize it — his aides kept warning him that he needed to tend to the party’s base to stave off primary troubles, but Crist wouldn’t listen.

As for the near future, the obvious question is over what, exactly, Crist will do, and when he’ll likely make his move. But I also wonder how fierce Republicans will be if/when he makes the leap and announces an independent bid. The GOP is vicious as a matter of course in campaigns, but their rage towards those who’ve betrayed them is usually even worse.

And then there’s that other matter: if Crist were to win an independent bid, who would he caucus with in 2011?

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.