They have given the nation a good close look at a Republican Party that no longer resembles the Bush-McCain model.
Consider. Michele Bachmann and Ron Paul, who garnered nearly 60 percent of the votes cast, were both among the two dozen House members who voted against the final bipartisan deal to raise the debt ceiling. Neither blanched at shutting down the U.S. government.
At the debate, every Republican onstage raised his or her hand when asked whether he or she would reject a budget deal in which $10 in spending cuts were offered for every dollar in higher taxes.
This is a party whose feet are set in concrete. The United States government will be downsized and tax rates will rise only over its cold dead body. This is Reaganism on steroids.
Bachmann's victory was stunning.
Every other candidate had been in Iowa organizing before she ever got into the race seven weeks ago. Yet she emerged with nearly 5,000 votes, the largest total ever amassed in an Iowa straw poll, with the single exception of George W. Bush's tsunami in 1999.
While virtually every candidate shares Bachmann's social and economic conservatism, none matches her fire and passion. She both humiliated and eliminated Tim Pawlenty, a fellow Minnesotan who had been her governor when she was a state legislator.
She is now not only the favorite in the Iowa caucuses but also one of three front-tier candidates for the nomination.
Ron Paul, however, who ran only 150 votes behind Bachmann and doubled the vote of Pawlenty, has not received the attention or credit his tremendous showing deserves.
Four years ago, Paul, a libertarian legend, was winning every telephone poll taken after a GOP debate but failing to win, place or show in the primaries. He seemed to be campaigning simply to make his case, realizing that he had no chance of being nominated.
His views on foreign policy were regarded as aberrational by fellow candidates, such as Rudy Giuliani, when they were not being ignored.
In last week's debate, Paul denounced U.S. intervention in wars that are none of America's business, called for closing U.S. bases abroad and bringing our troops home, and squared off against former Sen. Rick Santorum on whether Iran represents a threat.
Santorum and Pawlenty supported confrontation with Iran. Yet both together did not come close to matching Paul's vote tally.
The warfare state is now on the chopping block, thanks to the principled relentlessness of Ron Paul. And the GOP may soon become a house divided, for the anti-interventionists -- after Iraq, Afghanistan and Libya -- are stronger than they were in 1999, when the GOP House opposed Clinton's war on Serbia.
The entry into the race of Gov. Rick Perry of Texas, the only mega-state that is reliably Republican in presidential elections, has produced another front-tier candidate and complicated the strategic plans of Mitt Romney.
Had Perry not gotten in, Romney might have held to his decision not to make a huge investment in Iowa, let Bachmann or Paul win the state, and then dispatch them in New Hampshire and go on to rout them in a 50-state battle, for which he is better-resourced than any other candidate. Today he faces a new situation.
With Perry going into Iowa, the caucuses, from Christmas on, will rivet the nation's attention. If Romney is not there, he will be ignored for that month. And should Perry win Iowa, he would storm into New Hampshire and conceivably overwhelm Romney in his fortress state.
If he did, it would be all over for Mitt. For no GOP candidate ever has lost both the Iowa caucuses and the New Hampshire primary and won the nomination.
Should Bachmann prove to be a giant killer and defeat Perry in Iowa, she would be a formidable rival to Mitt in New Hampshire and a favorite to beat him in South Carolina.
There are two questions Mitt should be asking himself:
"Can I afford to cede Iowa to a tea party-values candidate like Perry or Bachmann and wait for them in New Hampshire? Can I take five months of pounding for 'writing off Iowa' and refusing to get out of my backyard and do battle in Middle America?"
Yet the entry of Perry and straw poll are not all bad news for Mitt. Pawlenty, who appealed to the same Republicans, is gone. And still in Iowa are Bachmann, Paul, Santorum and Perry, all of whom will be competing for the same social conservative-tea party base.
Which leaves a huge opening for Mitt.
Does he head for Iowa, confront Bachmann and Perry, and win, in which case he is the nominee? Or does he wait for Bachmann or Perry to come into New Hampshire on the momentum of an Iowa victory and try to stop them there?
Upon Mitt's decision may hang his five-year investment in winning the office his father failed to win.