Any credible account of the career of U.S. senator Saxby Chambliss, a Georgia Republican, must acknowledge this salient fact: He is conservative. He’s no maverick who managed to win a powerful office in a crimson state despite staking out positions that challenged the beliefs of his base.

He has opposed abortion rights, gay rights and government regulations on business. The American Conservative Union, whose ratings are considered the gold standard for grading elected officials on adherence to conservative dogma, gives him a lifetime score of 92.5 out of 100.

Still, Chambliss now finds himself under fire from right-wing extremists in the Republican Party — absolutists who believe that even a handshake with President Obama is a dangerous sign of collaboration with the enemy. So the senator will retire in 2014 rather than face a primary challenge from the right.

This is another unsettling development for the GOP, another sign of a party engaged in civil war. If Saxby Chambliss does not meet the standard for conservatism, then Republicans are doomed to bloodletting well into the foreseeable future. If a score of 92.5, which usually counts as an A, doesn’t pass muster, then the GOP is starting down the road to extinction.

The rabid right’s hostility to Chambliss grows out of his membership in the “Gang of Six,” a bipartisan group of senators who have toiled over the last couple of years to come to a compromise that would begin to eliminate federal budget deficits. Though he signed onto anti-tax activist Grover Norquist’s no-tax-increase pledge when he first sought a congressional seat, he has lately begun to voice doubt about its usefulness — as any reasonable person would.

If Tea Partiers were as worried about red ink as they claim, they would throw Chambliss a parade and hail him as a hero. But they’ve begun muttering about his conservative bona fides instead.

Last year, Georgia blogger Erick Erickson, a leader of the right-wing faction, wrote: “Saxby has consistently stabbed conservatives in the back and it is time to take him out.” By the time Chambliss voted in the earliest hours of New Year’s Day to support a tax hike on Americans earning more than $400,000 a year — a deal which, by the way, cemented in place George W. Bush’s tax cuts for everyone else — he was doomed among the absolutists.

Chambliss has said publicly that he’s not running from a primary challenge, but instead leaving a Congress that he finds dysfunctional.

But he is disingenuous — “The one thing I was totally confident of was my re-election,” he told reporters last week — in suggesting that the prospect of a primary challenge didn’t factor into his plans. He might have won, but he would have been forced to defend his decision to employ negotiation and compromise with his Democratic colleagues, strategies Republican extremists despise. He would have encountered rabid challengers willing to accuse him of grotesque crimes against party dogma. And he may have been forced to renounce the statesmanlike image he has spent the last few years building.

The senator is right about this much: Politics has become ugly and ruinous, especially inside the Republican Party. He joins a list of towering conservative figures who have left office — or been run out — after encountering the lunatic ravings of the crazed ultra-right. That includes Bob Bennett of Utah and Richard Lugar of Indiana, GOP stalwarts who lost to challenges by ultraconservatives.

And who might replace Chambliss? Several Georgia Republicans are eyeing the race, including U.S. representative Paul Broun, who told a church audience last year: “All that stuff I was taught about evolution and embryology and Big Bang theory, all that is lies straight from the pit of hell.” Broun, by the way, is a physician who sits on the House Committee on Science, Space and Technology.

Obama and other Democrats — as well as many moderate Republicans — have wondered how long it will be before the raging fever breaks on the rabid right. Well, by the time it does, the patient — the Republican Party — might be dead.

(Cynthia Tucker, winner of the 2007 Pulitzer Prize for commentary, is a visiting professor at the University of Georgia. She can be reached at cynthia@cynthiatucker.com.)

Photo by Bruce Tuten/Flickr