Some users noted  the system might simply be temporarily overwhelmed and suggested users wait a moment and then try again.

In an emailed statement, Microsoft said that the mobile apps for both parties worked without issue.

However national interest in the Iowa Caucuses overwhelmed the Democratic and Republican Party Iowa Caucus websites, which Microsoft was working to resolve, the company said.

Some online  charged that Microsoft founder Bill Gates had donated "millions" to the Clinton Foundation, making the company's creation of the apps suspect. However Microsoft created apps for both the Republican and Democratic parties, so others said that seemed unlikely.

Columnist Matt Drudge tweeted, "Watching the Iowa folks put their votes into Microsoft app is terrifying..."

Microsoft provided the free app in hopes of cutting down on errors and increasing speed in the reporting process, in response to issues at previous Iowa caucuses.