Bennett, who had spent the past two decades as a respected insider in the Senate, came under fire in recent months for what some claimed were his insufficient conservative bona fides.
Bennett's critics cited his vote for the Troubled Asset Relief Program (TARP) as well as his seat on the Senate Appropriations Committee symbols, conservatives said, of his lack of commitment to shrinking the size of government.
While state Republicans had expressed uneasiness with Bennett, it was the DC-based Club for Growth that helped crystallize that opposition. The Club spent more than $200,000 on a combination of television ads, direct mail pieces and phone calls designed to influence the 3,500 (or so) delegates who attended Saturday's state convention.
Under convention rules, all eight candidates appeared on the first ballot. The top three -- attorney Mike Lee, former Congressional candidate Tim Bridgewater and Bennett (in that order) advanced to the second round of balloting.
Bennett was defeated as Lee, a former counsel to popular former Governor Jon Huntsman, and Bridgewater, who had lost two races against Representative Jim Matheson (D), advanced to the final ballot.
Bennett said he has not ruled out a write-in campaign. His defeat marks the first time a sitting Senator has lost in an intraparty fight since 2006 when Senator Joe Lieberman was ousted by wealthy businessman Ned Lamont in the Democratic primary. Lieberman went on to run and win as an independent; under state law Bennett cannot pursue that course.
It also marks the first major victory for the conservative wing of the Republican party, which has organized itself under the banner of the Tea Party movement to protest what they believe to be a government run amok.
Bennett, a reliable conservative on most issues, had repeatedly expressed exasperation at his predicament -- insisting that the ideological right's issues with him were less about his record and more about the tone he struck during the partisan warfare in Washington.
Tea party supporters from across the nation had targeted Bennett as part of the problem in Washington and, with his defeat, are almost certain to be further energized to beat other GOP incumbents and candidates who they feel are not representing the core values of the party.
The next race to watch in the ongoing fight between the GOP establishment and the tea party wing of the party is in Kentucky. Ophthalmologist Rand Paul, who has the strong backing of the tea party movement, is facing off against Secretary of State Trey Grayson, the handpicked candidate of McConnell, on May 18 for the Republican Senate nomination.
Polling suggests Paul is the favorite although Grayson has rolled out several potentially influential endorsements in recent days including that of McConnell.