A poll observer identified the error that resulted in Milwaukee officials' decision to rerun approximately 31,000 absentee ballots earlier today.
Milwaukee's top election official said that the city's election results will likely be reported in the "early morning hours" after an error at a central processing location forced a retabulation of 31,00 ballots.
Milwaukee Election Commission Director Paulina Gutierrez said the error was identified by a poll observer -- a member of the public who watches election officials for the sake of transparency.
The Trump criticized Milwaukee election officials for the error.
"This is an unacceptable example of incompetent election administration in a key swing state: voters deserve better and we are unambiguously calling on Milwaukee's officials to do their jobs and count ballots quickly and effectively," RNC Chairman Michael Whatley and Co-Chair Lara Trump said in a statement.
"It's a human error," Gutierrez said. "That is the point of central county elections, is that it's transparent, and the observers brought it to our attention."