The field of Democratic presidential candidates vying for the nomination has remained relatively stable compared to past years, says Iowa State University’s Dave Peterson.

In past election cycles, candidates have come out of nowhere, surged ahead and eventually fallen back. Peterson, a professor and Whitaker Lindgren faculty fellow of political science, says that hasn’t been the case with the top tier of candidates in 2020.

“There hasn't been a breakthrough candidate reach anywhere near the top four and those top four have stayed the top four, none of them have fallen dramatically,” Peterson said.

Peterson has conducted monthly polling leading up to the Iowa caucuses. He is available for interviews to discuss polling, voter behavior and campaign strategy.