DES MOINES, FEB. 1 -- George Bush recently found a sure-fire way to drive Iowa Republicans wild, and it wasn't by zapping a network anchorman.

All he had to do was get tough with The Des Moines Register.

It happened at last month's Des Moines Register debate for the Republican presidential candidates, when the newspaper's editor, James P. Gannon, asked Bush why he wouldn't reveal his role in the Iran-contra affair. The vice president insisted that he already had.

Then Bush added, "Your paper today had that question raised as if I hadn't answered it. And I resent it, frankly." Suddenly thousands in the Des Moines Civic Center began to beat their hands together.

"You owe me now," Bush went on, as the applause built to a roar.

"You owe it to me to ask me the question that I haven't answered!" The building shook.

"YOU OWE ME IN FAIRNESS!" A thunderclap.

"Now ask it! What is it?"

Gannon looked stricken. The Register's chief political reporter, David Yepsen, lowered his eyes to his notebook. Cartoonist Brian Duffy slunk down into his seat.

"Barbara Bush was sitting right ahead of me, and Pat Robertson's wife and daughter were four seats away," Duffy recalled. "I felt kind of hemmed in. I wanted to cringe."

The Des Moines Register saturates the first-in-the-nation caucus state: 225,000 households daily, 375,000 Sunday, a news medium nonpareil for Iowa's 3 million citizens.

More important, a recent study concluded that the paper is read by 58 percent of the people who will influence the course of American politics at next Monday's presidential extravaganza.

A bastion of progressive Republicanism under the stewardship of Gardner Cowles in the early part of the century, the paper, part of the Gannett chain, is today more progressive than Republican. But unlike the Manchester Union Leader, the dominant paper of the New Hampshire primary, The Register's reputation is unsullied by rabid partisanship. Besides, it even has a smokeless newsroom.

"It's really the bible of Iowa," says syndicated columnist Jules Witcover. Thus it was big news Sunday when The Register broke with tradition to issue its first-ever editorial endorsements for the Iowa caucuses, urging Democrats to support Illinois Sen. Paul Simon and Republicans to vote for Kansas Sen. Robert Dole.

The paper ridiculed Bush for having favored "a bone-headed and amateurish foreign-policy ploy."

This morning in his weekly column, Yepsen rapped Bush's "sailor-mouth," referring to vice presidential expletives after the clash with CBS' Dan Rather. The column was accompanied by a Duffy cartoon of Bush engorged on a bar of soap. It was Duffy's third anti-Bush caricature of the week.

The other two appeared on The Register's front page, where The Register has published cartoons since 1906. This perhaps makes the soft-spoken, 32-year-old Duffy Iowa's answer to Nackey Loeb.

"I have nothing to say about The Register," said Bush's Iowa campaign manager, Rich Bond. "I've decided I'm going to control myself."

Aside from aggressive political coverage, the paper since 1980 has sponsored presidential debates and, since George Gallup was commissioned to do the first in 1943, the Iowa Poll. The last sounding of the caucus horse race will be published on Sunday.

"The poll has a very strong effect on candidates," says Witcover. "They watch it as though it's the tablets on the mount."

The effect of all this is strangely synergistic: Until Feb. 8, The Register has clout far beyond its circulation area -- its columns plumbed for political wisdom by the national press and quoted by political insiders as though visions from an oracle.

On Feb. 9 it goes back to being a midsized regional newspaper. The phenomenon is known hereabouts as the Cinderella Syndrome.

It is, as The Register reminds its readers under the bright red front-page logotype, "The Newspaper Iowa Depends Upon."

It's a phrase often mined for sarcasm in the Iowa state legislature, where members beat the rolled-up morning edition against their desks while complaining of the latest indignity. Sometimes detractors refer to the paper as "The Red Star" and "The Rag."

"Particularly in Republican circles, it's fairly common for candidates to run against The Register," says Gannon, whose neatly trimmed beard and wire-rimmed glasses lend him an aspect of earnest sagacity. "And," he added, invoking the memory of Bush, "it's always good politics to beat up on a bearded editor."

Not that the paper is known for its loyalty to Democrats.

"The Register is capable of fragging you," says Iowa's Democratic speaker of the House, Donald Avenson, who is working in Missouri Rep. Dick Gephardt's campaign. "They can open the door, throw in the grenade, and boom, you're finished."

"I don't like that word 'power,' because I'm not on a power trip, I'm not on an ego trip," says Yepsen, 37, who divides his time between writing stories and columns (218 bylines last year) and appearing on "Nightline." "I have a job to do."

Yepsen was one of the first reporters to detect evangelist Robertson's Iowa potential, helped break the story of Sen. Joe Biden's (D-Del.) plagiarism problems and coined one of the political season's more memorable phrases: "attack video."

Candidates fall all over themselves to enter his good graces. Once, when he asked former Delaware governor Pete du Pont's campaign for a position paper, du Pont showed up in the news room to deliver it personally.

The newspaper has been a force in presidential politics at least since 1972, when the date of the caucuses was moved ahead to preempt the New Hampshire primary as the first test of candidates' strength. That year, George McGovern did better than expected against Democratic front-runner Edmund Muskie.

McGovern actually got fewer votes than Muskie, but the event was heralded by The New York Times in a front-page story, and Iowa's place in American politics was assured. So, as it happened, was The Register's -- although not everyone sees that as good.

Drake University political scientist Hugh Winebrenner, for one, sees the caucuses as nothing more than a "media event," and The Register as little more than a "cheerleader."

For example, editorial editor James Flansburg, mad at Tennessee Sen. Al Gore for deriding the caucuses as too byzantine and Iowa as too liberal, branded Gore "the Richard Nixon of Democratic politics."

"In some ways," says Richard M. Cohen, senior political producer for CBS News, "The Register has become a chamber of commerce for Iowa in its knee-jerk and unthinking defense of the caucus system . . . They have become so much a part of the process here they're no longer capable of any intellectual honesty."

"I don't think the endorsement of candidates is a particularly good move," Cohen adds. "The paper is already perceived to be political enough. It's just one more dimension of The Register making themselves part of the process that they're trying to cover."

"We're obviously very deeply involved," says Gannon. "I'm sure there are some things I could say about CBS, but I won't."

In the meantime, the Dole and Simon campaigns were savoring The Register's vote of confidence.

"It makes you feel good, but we don't think it's going to make a big difference in our turnout," says Dole campaign spokeswoman Katie Boyle.

"It's clearly a big shot in the arm for us," says Simon's Iowa campaign manager Pat Mitchell. "In a race as tight as this one is, it will weigh pretty heavily."

That thesis will be tested finally on Monday.

Until then, The Register will continue to wield its brand of influence. It will be courted by the candidates and celebrated by the national press.

And after that, it will be ignored.

"It will be a great relief," says Yepsen. "I'll be able to play with my daughter."

"It won't be as crazy and I won't get interviewed as much, but this is a very lively, interesting place," Gannon says. "Iowa is a great place to run a newspaper."

But in a recent column, he betrayed rawer feelings when he warned his readers: "{T}he thing to remember is that on the morning of Feb. 9, the platoon of candidates and the army of national media will pack up and fly away.

"And then nobody will give a damn about Iowa except Iowans."