The political bias referenced in the intelligence community inspector general report is that the whistleblower is a registered Democrat, a source familiar with the investigation said.
Inspector general Michael Atkinson acknowledged the bias in his report, though said it doesn't change the facts of the complaint.
Here's what he wrote:
"Further although the ICIG's preliminary reviewed identified some indication of bias of an arguable political bias on the part of the complainant in favor of a rival political candidate, such evidence did not change my determination that the complaint relating to the urgent concern 'appears credible' particularly given the other information the ICIG obtained during its preliminary review."
Mark S. Zaid, an attorney for the whistleblower, took to Twitter to respond to the bias complaint, saying, “We won't comment on identifying info but if true, give me a break! Bias? Seriously? Most ppl are.”
He went on to say, “Partisanship not involved. Don't let anyone argue differently.”