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."