While the biggest political story this year has been the Democratic Party's fight to retain its majorities in Congress, a fascinating back-story is developing: the very conservative, populist revolt taking place within the Republican Party.
The first development occurred in April 2009 when five-term Pennsylvania Sen. Arlen Specter left the Republican Party to become a Democrat, believing there was little chance he could win a Republican primary against former Rep. Pat Toomey. While this was not exactly a "stop the presses" event, it was still notable that a moderate incumbent would decide he had no future in his party, particularly in a swing state like Pennsylvania.
The next incident was Florida Gov. Charlie Crist's abandonment of the Republican Senate primary -- where he had fallen far behind former state House Speaker Marco Rubio in GOP primary trial heats -- to run as an independent.
Crist's problems started with an unfortunate hug of the Democratic president at an event promoting the economic stimulus package; both that package and President Obama have since become radioactive to the GOP base.
Crist is a politician straight from central casting, and he got caught in a year when being perceived as such is a problem. All this, coupled with the fact that Rubio has become a darling of the conservative movement, meant that Crist had little choice but to get out of the primary. It is particularly unusual for a sitting governor, the titular leader of a party in any state, to be hounded out of a primary.
This past weekend, though, gave us one of the most interesting stories of this conservative revolt, when three-term incumbent Sen. Bob Bennett came in third place at Utah's Republican convention, denying him a place on the June 22 GOP primary ballot.
As someone who has greatly admired Bennett and sees him as one of the most responsible members of the Senate, the growing realization over the last six months that he was in trouble was itself deeply troubling.
More than anything else, Bennett became the first major victim of the Troubled Asset Relief Program, the rescue package enacted after Lehman Brothers fell, the worldwide credit markets seized up and the U.S. economy went into cardiac arrest.
While it may have prevented us from falling into a second, much more complicated Great Depression, it did enrage many Americans who saw it as a dangerous governmental overreach and helped launch the Tea Party movement.
By any rational standard, Bennett is a true conservative, just not enough of one in the minds of the delegates to the Utah Republican convention for him to make the ballot.
All of Bennett's other problems, though, pale in comparison with TARP.
Utah's senior Sen. Orrin Hatch, who supported TARP along with Bennett and 72 other members of the Senate, privately told others he doesn't think he'd be able to win a Republican primary if he were facing re-election this year.
Republicans are very lucky that they don't have more House or Senate incumbents who supported TARP facing competitive primaries this year.
Against this backdrop, Sen. John McCain of Arizona, the 2008 Republican presidential nominee, is fighting for his political life, facing an aggressive challenge from former Rep. J.D. Hayworth.
McCain seems to have the inside track at the moment, but barely. History shows that well-known and well-defined incumbents generally lose the lion's share of undecided votes, which means that this race is really close to a 50-50 proposition.
While Bennett had never gone out of his way to offend conservatives in his state, McCain has a long track record of picking fights with the more ideological wing of his party.
The now-dropped "maverick" moniker was not exactly invented during the 2008 campaign, as McCain has always been a boat-rocker in his party. Given the hostile, anti-Washington environment and particularly the rebellion over TARP, it's a wonder that McCain is hanging on at all.
The truth is that McCain would be a dead man in this primary had he not seen this coming and begun repositioning himself. The political climate for a Republican who has long relished poking his party's ideologues in the eye is awful.
In a year when a Bob Bennett isn't conservative enough, McCain would seem likely to be a goner. But McCain has reached out to old foes and worked aggressively to keep neutral those who could do his re-election hopes great damage.
He has staked out the position of being among Obama's chief critics in the Senate, was exceedingly vocal in his opposition to the stimulus package and has shown a political dexterity that would make any gymnast envious.
Having written McCain off once before -- during the summer of 2007 to be very specific -- it would seem dangerous to do it again. If nothing else, McCain is a survivor and seems to have an even-money chance at surviving this primary challenge. Under the circumstances, those aren't bad odds.