Voters listen to Democratic presidential candidate Sen. Bernie Sanders during a campaign rally January 29, 2016, in Dubuque, Iowa.
Washington CNN  — 

CNN and The Des Moines Register will not release their final Iowa caucus poll, the network announced Saturday.

“A respondent raised an issue with the way their interview was conducted, which could have compromised the results of the poll. We were unable to ascertain what happened during this respondent’s interview, and cannot determine if this was a single isolated incident,” the network said in a tweeted statement.

“CNN, The Des Moines Register and Selzer & Company aim to uphold the highest standards of survey research and therefore the partners decided not to proceed,” the statement continued.

A source familiar with the decision said that a respondent reported that an operator, during a telephone interview, did not name former South Bend, Indiana, Mayor Pete Buttigieg when listing the 2020 Democratic presidential candidates.

The source added that it was determined a single terminal at a call center had its font changed, which cut off the last line of a randomized list of names. It’s unclear whether the issue occurred more than once or impacted other candidates.

“This is a high-pressure situation. Things came to light late in the process,” said J. Ann Selzer, whose company conducts the Iowa Poll. “There were concerns about what could be an isolated incident. I have two exceptional news partners working on deadline, and there came a time to decide what to do about the poll. Because of the stellar reputation of the poll, and the wish to always be thought of that way, the heart-wrenching decision was made not to release the poll. The decision was made with the highest integrity in mind.”

The poll was scheduled to be released at 9 p.m. ET on Saturday, two days before the February 3 Iowa caucuses.