Political circumstances can change unexpectedly, of course, but at the moment the Democrats seem very likely to lose seats in the 2010 midterms, and possibly quite a few of them. What's a little harder to predict is what will happen in the 2010 Republican primaries, where the number of insurgent, tea-party-propelled challenges to establishment candidates continues to multiply. The Charlie Crist - Marco Rubio smackdown in Florida is obviously the marquee event here but, as Politico notes, hardly the only one:

Tea party activists are also lining up behind challengers to GOP establishment-backed Senate candidates in Colorado and Connecticut. In California, former Hewlett-Packard CEO Carly Fiorina — like Crist, another National Republican Senatorial Committee-favored Senate contender — is the target of tea party animus in her primary against conservative state Assemblyman Chuck DeVore....

In a handful of states, tea party activists have zeroed in on House Republican incumbents and have launched primary challenges in protest of their past support for the controversial Wall Street bank bailout.... One of those activists, Canyon Clowdus, an Army veteran who is taking on third-term conservative Rep. Mike Conaway (R-Texas), has blasted the incumbent for making “a horrible mistake” in voting for Troubled Asset Relief Program.

 That's not even taking into account the sneak-preview we'll get in the special election for New York's 23rd District this November, where Doug Hoffman, running on the Conservative Party ticket, is making what ought to be an easy victory for GOP candidate Dede Scozzafava considerably less certain.

There's been a lot of talk--and rightly so--about how the Republicans will have a far more motivated voter base in the off-year election. But these insurgencies illustrate that this can be something of a mixed blessing. Whether the tea-party challengers win (which I doubt many will), and provide less general-election friendly nominees, or lose, and depress the base's enthusiasm for the establishment victors, they could be a significant bump on the road to large GOP gains.