Every candidate for the Republican nomination has campaigned at Pizza Ranch, a beloved restaurant chain in Iowa with strong ties to the Christian right.

Every candidate except Mr. Romney. His campaign prides itself on a vigilance and meticulousness bordering on the obsessive. So before Mr. Romney appears at a campaign stop or accepts an endorsement, his staff conducts sometimes painstaking vetting to avoid potentially embarrassing disclosures.

A founder of Pizza Ranch, it turned out, spent time in prison on charges of sexually abusing male employees. “There is not a lot of room for mistakes,” said David Kochel, Mr. Romney’s top strategist in Iowa…

The wide gap between the figures for Mr. Gingrich and Mr. Santorum say much about their organizations in Iowa, which has more than 1,700 precincts.

As of midweek, Mr. Santorum, who traipsed to even the most rural of Iowa’s 99 counties over many months, had secured speakers in 1,000 of the precincts. Mr. Gingrich, who opened an office here only a few weeks ago, had nailed down about only 200.

Though that number had doubled by the end of the next day, Mr. Gingrich’s own aides acknowledged that the shortage of speakers could be a problem. “Iowans have a deep belief in organization,” said April Linder, a Gingrich staff member, “and when you don’t have a speaker, it shows a lack of organization.”