Gowdy, a former South Carolina Republican congressman, made the claim Wednesday on "The Daily Briefing," adding dozens of Democratic lawmakers voted in favor of articles of impeachment before Mueller began his probe.
The ex-lawmaker said he believed Mueller's remarks will spur Democrats and other critics of Trump to embark on an "impeachment investigation" from now until the 2020 election.
"We'll be in this state of chaos for the next 14 months," Gowdy said. "What you're going to have now, for the next 14 months, is an impeachment investigation by folks who have already made up their mind. The jury's never going to convict him."
"I don't think there's a prosecutable case for obstruction," he added. "From what I have seen, firing Jim Comey is not obstruction."
Gowdy also fired back at House Judiciary Committee chairman Jerrold Nadler, who declared Wednesday Congress will "take action to hold the president accountable for his misconduct."
Rep. Nadler, D-N.Y., also claimed Trump is "lying about [Mueller's] findings, lying and saying the special counsel found no obstruction and no collusion."
"With respect to the impeachment question at this point, all options are on the table," he added.
"I noticed the word 'misconduct'," Gowdy said of the New York lawmaker's remarks. "I'm beginning to wonder whether we live in a country where there are any presumptions of innocence."