AMES, Iowa — Mitt Romney's Iowa team members awoke on a Sunday to find their BlackBerries buzzing with startling news: A major poll had Romney up — and up big — over his rivals for the Republican presidential nomination.

First, they were joyful; the survey by The Des Moines Register on May 20 showed Romney supported by 30 percent of likely Republican voters, compared with 18 percent for Arizona Senator John McCain and 17 percent for former New York mayor Rudy Giuliani. But apprehension soon followed.

At 10:21 a.m., Christopher Rants, the Iowa House minority leader and a top Romney adviser in the state, sent an e-mail to senior campaign staff before he left for church. The subject line read, "Too early to look too good."

Indeed, the poll results — as well as a surge in other recent Iowa surveys — have put Romney in an unfamiliar spot: For the first time, he can claim front-runner status in one of the critical states, a designation that seemed unthinkable just months ago.

Romney's early success, according to advisers, supporters, political analysts and Republican activists, is due in large part to his aggressive and well-organized campaign operation in Iowa.

He has flooded airwaves statewide with early TV ads, the only leading candidate to do so. He has inundated voters with campaign fliers and DVDs containing a hagiographical video. He has visited the state repeatedly. And he has spent the past few years strategically courting key party players, doling out campaign cash to county GOP groups and local candidates.

These are precisely the organizational strengths Romney needs to succeed in the first true Iowa test, which comes this summer: an August straw poll in Ames that will set the course of the race here for the rest of the year.

The importance of the straw poll is evident at Romney's Iowa headquarters in Urbandale, where there are two countdowns on the walls — one showing the number of days to the projected date of the caucuses, Jan. 14, and one showing the days until Aug. 11, a Saturday, when the straw poll will draw 50,000 Republican activists to Iowa State University.

"The number one challenge of the campaign now is how to translate this success in polling to people on the ground in Ames," Rants said. "People now expect us do to well and no one has a clue what is going to happen that day. Will it be 110 degrees outside? What if it rains? What if something happens in some part of the state? And that is not even getting into competing with family reunions, softball games, picnics, and stuff people do on the weekends."

The straw poll is a storied event in Republican presidential politics, a mega fund-raiser-cum-horse race that tends to be a good predictor of who succeeds in the caucuses. Since the first straw poll in 1979, every candidate who has won the caucuses has performed well in Ames. Conversely, poor performances in the straw poll have ended campaigns. One 2008 Republican candidate, former Wisconsin governor Tommy Thompson, has said his campaign is effectively dead if he doesn't finish in the top two in Ames.

Romney is already seeing positive signs. In the Des Moines Register poll, he fared even better among likely straw poll participants, winning 34 percent to Giuliani's 16 percent and McCain's 15 percent.

But the best indicator might be his strong organization, which is essential for getting supporters to the Ames poll. Romney made a savvy move early in signing up Gentry Collins, a well-regarded former executive director of the state party. Collins, as Romney's state director, now leads a staff of 16 people. Romney also spent $77,000 in the first three months of 2007 for the services of Nicole Schlinger, a fund-raising and organizing specialist who is helping lead Romney's straw poll efforts.

"The man is organized, and the people are good," said Susan Frazer, a former Republican county chairwoman in Scott County, Iowa, who said she likes Romney but remains undecided.

One small window into the campaign's ground game came a few weeks ago, when Nick Lantinga, an influential GOP activist from northwest Iowa whom Romney has courted, stopped by a Thompson event at Family Table Restaurant in Sioux Center. Hours after he got home, Lantinga said, he received a phone call from a nearby city councilor who is also a volunteer for Romney's campaign.

"What are you doing there?" Lantinga, who is undecided, said he was asked.

Iowa, because it votes first in the primary season, wields outsized power in the presidential nominating process, often making or breaking campaigns for the White House. Though Iowa caucus-goers have had mixed success in selecting the eventual nominees, a win — or at least a strong showing — in the state delivers a major lift.

Romney's advisers are sanguine about his chances, but they are not taking anything for granted. And they know that being the front-runner invites a whole new set of unwelcome expectations.

Alex Gage, a Romney campaign strategist, used a recent memo to supporters to try to dampen expectations. "While we should feel good about coming so far so quickly, we should also not lose sight of the fact that our early lead in Iowa and New Hampshire today guarantees nothing." (Gage's memo was first reported by The Hotline.)

Romney is helped by the complicated relationships the other top candidates have with Iowa. McCain skipped the state entirely when he ran for president in 2000, and his championing of immigration reform has cost him conservative support. He has, however, built a substantial organization of his own and has 17 Iowa staff members, one more than Romney.

Giuliani, who has nine Iowa staff members, hasn't decided yet if he will participate in the Ames straw poll.

Arthur Sanders, a professor of politics at Drake University in Des Moines, said the GOP establishment in Iowa, after faring poorly in the 2006 election, had "no natural presidential candidate."

"There really was an opening for someone like Romney, and he has certainly filled the gap," Sanders said.

But other Republicans are putting up a fight, notably Thompson and Senator Sam Brownback of Kansas, a favorite of social conservatives, who make up a disproportionate percentage of Iowa caucus-goers. Former Arkansas governor Mike Huckabee, meanwhile, delivered the commencement address at Des Moines University on Saturday.

Romney's opponents aren't wasting any time trying to knock him down, already questioning how strong his Iowa support really is, attributing his bump in the polls to his TV ads, and taking aim at his shifting positions on abortion, immigration, and other issues.

McCain's Iowa chairman, David Roederer, acknowledged that Romney is doing well but questioned whether he has staying power. "You have to make sure you don't peak too early," said Roederer, who chaired the 2004 Bush-Cheney re-election campaign in the state.

Romney returns to Iowa today for one of his "Ask Mitt Anything" public forums, and he and his surrogates will surely spend much of the summer flying in and out of the state. Not all of them will be flying, though: Romney's son Josh has bought a big RV, christened it the "Mitt Mobile," and made plans to visit all of Iowa's 99 counties.