CARROLL, Iowa — When I asked Rob Sand, the Iowa state auditor, if he could recommend fascinating Iowans to profile, he suggested himself. Then he suggested we go deer hunting.

“We can get you in a tree stand this week to spice it up,” he said in a text.

Mr. Sand’s fondness for hunting — cultivated during his childhood years in rural Iowa but also conveniently appealing to the state’s more conservative constituents — helps explain why he was the only non-incumbent Democrat to win statewide here in 2018. And that, in turn, helps explain why he has become one of the most sought after endorsements in what could be the most important state in the most important presidential primary for Democrats maybe ever.

Over the last year, many of the 2020 candidates have asked him for advice, viewing him as a next-generation oracle of rural Iowa but also as a model for how to win as a Democrat in a state that President Trump captured in 2016 by more than nine points.

Pete Buttigieg, the mayor of South Bend, Ind., had coffee with him in February and recently called him to talk about agricultural policy. Elizabeth Warren met with him at a coffee shop during a recent visit to Des Moines. He speaks frequently to Cory Booker. Michael Bennet gave him his book. Terry McAuliffe, the former governor of Virginia, had breakfast with him when he was thinking about getting into the race.