Nationally, roughly 14 percent of Warren supporters have said that Buttigieg is their second-favorite primary candidate, according to the most recent data from Morning Consult. But only about 3 percent of Sanders backers said the same. In Iowa, the contrast is even more stark. Some 20 percent of Warren supporters in the state said their next choice would be Buttigieg, according to a new poll from Civiqs and Iowa State University, compared with 3 percent of Sanders backers.

This disconnect may have meaningful implications for the race going forward: If Buttigieg continues to surge in Iowa, at least some of Warren’s supporters could be poised to give the Indiana Democrat another look. But more broadly, the distinction reveals very real differences between Warren and Sanders as candidates and the voters backing them.

Read: Pete Buttigieg isn’t going anywhere

Over the past month or so, Warren and Buttigieg have developed a kind of campaign rivalry. Buttigieg has repeatedly criticized the senator from Massachusetts for dodging questions on Medicare for All, while Warren has accused him of not dreaming big enough. It’s surprising, then, that so many of Warren’s supporters say they like Buttigieg. Sure, some worry that he’s a bit green, having served in elected office only as the mayor of Indiana’s fourth-largest city. But they’re taken by his personality and his résumé, and they’re tempted to consider his more incremental approach on issues such as health care. When I asked them about Buttigieg, Warren supporters used words like “refreshing” and “charming” and “bright.”

Herring noted that Buttigieg isn't among her favorite 2020 candidates. Still, she said, “I’m very impressed with his story." The son of two Notre Dame professors, Buttigieg grew up in the industrial Midwest, went to Harvard (where Warren was a longtime professor), and became a Rhodes Scholar. Later, he joined McKinsey as a consultant and served as an intelligence officer in the Navy Reserves. “I’d like to believe that he’s the future … as far as getting young people engaged,” Herring said.

Some Warren voters I spoke with, including Herring, criticized Buttigieg for not supporting Medicare for All and instead proposing a narrower universal health-care plan, which he has branded “Medicare for All Who Want It.” But for others, this adds to the small-town mayor’s appeal. Logan Benson, a 23-year-old student at the University of Northern Iowa, said he is eyeing Buttigieg because the mayor’s views on health care seem less radical and more reasonable than Warren’s or Sanders’s. “He does a good job of bringing in progressive supporters [while] leaving choice in the equation,” Benson said, citing Buttigieg’s support for a public option. “I think that’s going to help him out a lot here [in Iowa]. That’s why he’s going to do well.”