An Iowa poll released Thursday puts Pete Buttigieg, the openly gay mayor of South Bend, Indiana, in second place after Massachusetts Senator Elizabeth Warren.

According to the latest Iowa State University/Civiqs poll, 20 percent of 598 likely caucus-goers picked Buttigieg as their choice for the Democratic presidential nomination.

Twenty-eight percent of respondents chose Warren.

Dave Peterson, a faculty fellow in political science and professor at Whitaker Lindgren, said that Buttigieg's organizing in Iowa is paying off.

“You can attribute some of his momentum to basic retail politics,” said Peterson, who organized the poll. “Buttigieg is incredibly well organized and is spending a lot of resources in Iowa. His presence at the Iowa Steak Fry last month was better than any other candidate.”

Vermont Senator Bernie Sanders is in third with 18 percent, while former Vice President Joe Biden is in fourth at 12 percent.

The poll was conducted online.