No one doubts the sincerity or power of the Tea Party movement anymore. We get it: free market principles, limited government and individual liberty.

Those are the three fundaments of the Tea Party’s “Contract from America,” to which any serious Republican must subscribe, nay, sign in blood. Make it real red.

Nowhere is this new power-to-the-people imperative in starker relief than in Utah — one of the nation’s reddest states — where three-term conservative Sen. Bob Bennett seems likely to lose the Republican Party nomination this weekend.

This, despite the fact that Bennett earns an 84 rating from the American Conservative Union, an A ranking from the National Rifle Association — and is nothing like a liberal.

But Bennett committed the ultimate sin in Tea Party circles. He voted for the Troubled Assets Relief Program (TARP), aka “bank bailout,” during the George W. Bush administration. And he advanced a market-driven health care reform bill as an alternative to the Democratic plan that, alas, also included an insurance mandate.

Never mind that a Republican president proposed the bailout, or that many Republicans and free marketers felt TARP was crucial to keep the economy from capsizing. For those who have forgotten, the point was to prop up the credit system to keep enough money flowing so that the “free market” didn’t collapse entirely.

What was the alternative? What might have happened without TARP? As Mitt Romney, who supported TARP, has said, “We were on a precipice. … Now we can sit back and say, ‘Oh, it wasn’t so scary.’ Well, frankly, it was a very scary time for a lot of people. And that’s something which was resolved.”

Tea Partiers mostly upset about subsequent spending have cast a wide net and any incumbent is liable to be snared — even the good ones, such as Bennett, who is widely respected in Washington and has been endorsed by establishment Republicans Newt, Mitt & Karl (Gingrich, Romney and Rove).

Then again, being an establishment favorite in an anti-Washington environment may be as disadvantageous as having an Ivy League degree. Those out-of-touch elites, you know.

But in their rush to banish all but the purest fiscal conservatives, Tea Partiers risk losing some of their strongest voices and diminishing their power in an arena where relationships matter. Bennett, for example, worked with Democrat Ron Wyden to co-sponsor his health care proposal.

What non-ideologues may see as cooperation, however, is viewed by true believers as weakness. Any attempt at compromise is viewed as surrendering principle. Under the new order, a Good Conservative wouldn’t cross the aisle to perform a Heimlich maneuver.

The long-promised purge is on, in other words, and anyone fantasizing about bipartisanship can choke on that hope.

If Obamaphiles have been sipping Kool-Aid, Bennett’s primary challengers have been steeping in the bitter tea of an angry electorate. Indeed, more than two-thirds of delegates to the upcoming Utah Republican convention consider themselves to be tea party supporters.

Much the same is happening in other states. In Arizona, uber-veteran John McCain, whose American Conservative Union rating last year was only 63, is fighting for the Senate seat he has held for more than 23 years against Tea Party favorite J.D. Hayworth. In Indiana, Rep. Mark Souder was pummeled by car dealer-challenger Bob Thomas for his vote on TARP. In Florida, Marco Rubio has the tea winds at his back for the U.S. Senate nomination, which forced Gov. Charlie Crist to declare himself an independent.

Funny about that TARP vote, though, reminiscent as it is of the Iraq War vote that Barack Obama ran against but, not yet having been elected to the U.S. Senate, wasn’t called upon to cast. Would all those running against TARP now have voted against it had they been in Washington with the full weight of economic collapse on their shoulders?

It is certainly not objectionable that Americans reshuffle the deck now and then. Entrenched politicos become too beholden over time to special interests, as well as to the very relationships that sometimes can be useful to the common good.

But in purging impure Republicans from the ranks, Tea Partiers ultimately may manage to further shrink the GOP by alienating those repelled by purity tests. Nothing dissuades like righteousness. And though Tea Partiers pledge allegiance to no party, Republicans clearly are more aligned with their principles than Democrats.

If good-faith, conservative legislators such as Bennett fail to pass muster, who will be brave enough to legislate?

If no one, then what?

Kathleen Parker writes for the Washington Post. Her e-mail address is kathleenparker@washpost.com.