One volunteer leader enlisted by Donald J. Trump to turn out Iowa voters has yet to knock on a single door or to make a phone call. Another is a “9/11 truther” with a website claiming that the Sept. 11 attacks were a government conspiracy. A third caucus precinct captain, who like the others attended a training session in West Des Moines last month, said the campaign’s goal of having them each enlist 25 supporters was unrealistic.

“There’s probably not even 25 registered voters in a precinct,” said the captain, Kathy Hawk, a retired trauma therapist in Ottumwa, who began making calls only on Monday.

Mr. Trump, who Iowa polls show is neck-and-neck with Senator Ted Cruz of Texas, may well win the caucuses, now less than three weeks away. But if he does, it will probably be in spite of his organizing team, which after months of scattershot efforts led by a paid staff of more than a dozen people, still seems amateurish and halting, committing basic organizing errors.