“We love Huckabee,” Mr. Dixon said, recalling the 2008 Republican winner and a third-tier candidate now, “but it costs me a couple hundred bucks every time I do one of his rallies.”

The most popular merchandise? The ubiquitous “Make America Great Again” hat, and buttons with a Republican elephant wearing a Trump wig, one proclaiming “Hot Chicks for Trump” and another saying “Bomb the [expletive] out of ISIS,” echoing a Trump line.

These vendors, who included two out-of-work truck drivers and an unemployed cook, could easily have taken the place of a television commentator, since they follow the races just as closely.

“If Trump takes Iowa, he’ll probably take New Hampshire and go all the way,” Mr. Kriener, the unemployed cook, told me, presaging Monday’s cable TV punditry. “Hillary Clinton may win some delegates here but she will probably be indicted because of the 22 emails from yesterday. Joe Biden will step in at the last minute.”

But Will They Turn Out?

As I do at every Trump rally, I surfed the line of waiting attendees, in search of an answer to the greatest unknown of this year’s caucuses: whether Mr. Trump’s crowds will turn into a wave of caucus-goers. Of about 35 people, roughly two-thirds were still undecided. The rest were split between caucus “tourists” from out of state, who are ineligible to vote, and those planning to vote Trump. Almost all of the committed said this would be their first caucus, a very positive sign for the Trump campaign.