Fundamentalists are taking over the Republican Party. Not religious fundamentalists. The Religious Right has gained influence in the GOP but has never quite managed to take it over. Now it's political fundamentalists -- the tea party movement -- and their successes are mounting.

Religious fundamentalists have a total commitment to faith: Any wavering or compromise is unacceptable. Political fundamentalists have a total commitment to principle: Any politician who wavers or compromises is cast out as a heretic. That's exactly what happened to Sen. Robert Bennett, R-Utah. He was rejected by tea party fundamentalists who took control of Utah's Republican convention. Bennett's sin? His opponents taunted him with shouts of "TARP! TARP!" as he addressed the delegates, deriding his vote for the Troubled Asset Relief Program.

Religious fundamentalists scorn unbelievers. So do political fundamentalists. Florida Gov. Charlie Crist was forced out of the Republican Party for embracing President Obama, who tea partiers see as the anti-Christ. Sen. John McCain, R-Ariz., is in a race for his political life because he has collaborated with Democrats, i.e., unbelievers.

Religious fundamentalists have revival meetings. Political fundamentalists have rallies. Religious fundamentalists believe in the total inerrancy of the Bible. Tea party supporters believe in the total inerrancy of the U.S. Constitution -- as written in 1787.

Tea party supporters were horrified to learn that Supreme Court nominee Elena Kagan once wrote a law review article in which she seemed to agree with the late Justice Thurgood Marshall that "the Constitution, as originally drafted and conceived, was 'defective.'" To them, she was attacking Scripture! Republican National Committee Chairman Michael Steele advised the Senate to investigate Kagan for heresy. Only, it turns out that the "defect" Marshall was referring to was slavery.

Rand Paul is the new tea party hero. In Kentucky's Republican Senate primary, he slew the establishment candidate. Paul caused an uproar when he raised doubts about whether the federal government may outlaw discrimination by private businesses. Asked if a business should have the right to refuse to serve African-Americans, Paul responded, "Yes." He insisted that he personally opposes discrimination, but added, "One of the things freedom requires is that we allow people to be boorish and uncivilized."

The episode was reminiscent of another Republican fundamentalist, the late Sen. Barry Goldwater, who in 1964 voted against the Civil Rights Act on constitutional grounds. Goldwater was personally not a racist either. But his view that civil-rights legislation was an unwarranted expansion of federal power won him a lot of racist votes. The only states that Goldwater carried in 1964, in addition to his own state of Arizona, were in the Deep South, at a time when only Southern whites could vote.

Fundamentalists emerge whenever they believe that establishment Republicans have failed -- or betrayed them. The Goldwater movement felt betrayed by Eisenhower Republicans after 20 years of Democratic rule. The Reagan movement emerged after the failed presidencies of Richard Nixon and Gerald Ford. The tea party movement is not just a reaction to the sins of Obama. It's also a reaction to the failures of George W. Bush and his "Big Government" Republicanism. When "moderation" fails, fundamentalism rushes in.

How do we know it's taking over the Republican Party? Because Republicans are refusing to commit the cardinal sin of collaborating with Democrats.

With the impending passage of the financial regulation bill, Obama will have achieved three major legislative breakthroughs: the economic stimulus, health care reform, and financial reform. None of them has gotten more than a few Republican votes. Obama's achievements are all partisan. Fundamentalist Republicans can't wait to undo them.

In the end, the only force that can defeat fundamentalism is pragmatism. Religious fundamentalists fail because they seem out of date in the modern world. Political fundamentalists fail because they seem out of touch with reality. Like Paul, who said it was "un-American" for Obama to hold BP responsible for the Gulf oil spill.

Most Americans are religious but not fundamentalists. Most Americans agree with the principle of limited government but are not tea party activists. Still, Obama's achievements may not be safe. Only one thing can protect them: the perception that they are working. Pragmatism. So far, that perception has not taken hold for either the economic stimulus or health care reform. Until it does, Obama's legacy remains vulnerable to fundamentalist damnation.