Iowa Democratic leaders say they are troubled by the prospect that Hillary Clinton could win the state’s 2016 presidential caucuses without a serious challenge, a view primarily rooted in a desire for a more liberal candidate or at least a robust debate about the party’s policies and direction.

Interviews with more than half of Democratic chiefs in Iowa’s 99 counties show a state party leadership so far reluctant to coalesce behind Mrs. Clinton. County Democratic officials also voiced qualms about Mrs. Clinton’s ability to win a general election and her fundraising ties to Wall Street firms and corporations, which remain a target of liberal ire.

Many county officials said they would like to see senators including Elizabeth Warren of Massachusetts and Bernie Sanders of Vermont enter the race, though they were split over whether any could gain traction and overtake Mrs. Clinton.

“My heart wouldn’t be in it for Hillary to the extent that it might be if it was a different candidate,” said Jennifer Herrington, chair of the Page County Democrats in southwest Iowa. “I admire Hillary, she’d be a great president, but you know, she isn’t my first choice I guess.”

Of course, candidates can secure a party nomination without winning Iowa, an idiosyncratic contest that tends to reward candidates with strong local organization and passionate supporters. But as the first-in-the-nation contest, set to take place about a year from now, Iowa draws outsize attention from candidates and the media, and it can set a narrative for a party’s entire primary season.