The app being used to tally and report Iowa caucus results was sending "only partial data" due to a coding issue, the Iowa Democratic Party announced Tuesday morning.

"While the app was recording data accurately, it was reporting out only partial data," the Iowa Democratic Party said.

Iowa caucus results have been majorly delayed, and caucus precinct chairs complained of difficulty logging into the app.

The Iowa Democratic Party had previously said there were no technical issues with the app but declined to name a specific problem leading to the delays until now.

Visit Business Insider's homepage for more stories.

The results of Monday's Iowa caucus are delayed due to a "coding issue" with the app being used to tally and report data from caucus sites, the Iowa Democratic Party said in a statement Tuesday morning, NBC News reported.

The group said its "ultimate goal is to ensure that the integrity and accuracy of the process continues to be upheld." Results are expected to be released Tuesday.

"As part of our investigation, we determined with certainty that the underlying data collected via the app was sound. While the app was recording data accurately, it was reporting out only partial data. We have determined that this was due to a coding issue in the reporting system. This issue was identified and fixed. The application's reporting issue did not impact the ability of precinct chairs to report data accurately," the party said.

The party is now verifying reported results using paper documentation from each precinct.

Difficulties with the app go beyond the coding issue. Precinct chairs were reporting problems logging into the app as of Monday afternoon.

Many precinct chairs gave up on using the app entirely, opting instead to call in results via secure phone line. However, they reportedly faced long hold times when trying to dial in results.

Shawn Sebastian, a precinct chair in Story County, told CNN's Wolf Blitzer Monday night that he was on hold for over an hour waiting to report results. Shortly after the call connected, he said he was hung up on.

The app was new this year, and was created by Shadow, a mysterious DC-based tech company. Shadow was co-founded by Gerard Niemira and Krista Davis, a former employee of Hillary Clinton's 2016 campaign, according to The Los Angeles Times.

The Iowa Democratic Party previously kept the developer of the app a secret, and its name was first reported by The Huffington Post and The New York Times early Tuesday morning. According to the Times, the app was not tested under real-world conditions, and most precinct chairs had never logged into the app before the day of the caucus.

Shadow did not immediately respond to a request for comment.