Former White House press secretary and Fox News contributor Ari Fleischer told “Outnumbered Overtime” Thursday that it was “so incredibly stupid of Twitter” to fact-check President Trump’s tweets about mail-in voting Tuesday.

“This is the most foolish thing Twitter could possibly do,” said Fleischer, who later emphasized that “I will always come down on the side of more free speech is best.

“Twitter is a private company," he added. "They can be as dumb as they want to be, and they've proved to everybody how dumb they can be."

Fleischer spoke after Twitter CEO Jack Dorsey fired back at Facebook CEO Mark Zuckerberg, who told Fox News' Dana Perino in an interview airing on "The Daily Briefing" Thursday that private companies should not put themselves in the position of being "the arbiter of truth of everything that people say online."

TRUMP WARNS SOCIAL MEDIA GIANTS THAT FEDS CAN 'REGULATE' OR 'CLOSE THEM DOWN' AMID FIGHT WITH TWITTER

In a late-night thread posted Wednesday, Dorsey refuted Zuckerberg's comments while defending Twitter's "Head of Site Integrity" Yoel Roth over his hyper-partisan, anti-Trump tweets.

"Our intention is to connect the dots of conflicting statements and show the information in dispute so people can judge for themselves,” Dorsey said.

“Good luck Jack," Fleischer said in response. "Everything out there is a dot. Everything is somebody's opinion about something.

“Are you now going to regulate all that?"he asked. "Are you going to try and be the arbiter of it?"

“I'm not a fan of government interference in this because I believe the private sector has the right to be stupid," the former press secretary added, "but boy, did Jack Dorsey step in it."

Trump was expected to sign an executive order later Wednesday that could seek to curb legal protections for social media companies.

CLICK HERE TO GET THE FOX NEWS APP

Fleischer noted that Dorsey had “put up a platform to allow people to tweet, to allow people to enjoy speech and then for people to figure it out for themselves, as free people.”

“That’s a higher use of what Twitter should do,” he continued. “Stepping into it, especially for the first time against an American president -- he hasn't done that to the Iranian president, he hasn’t done that to Chinese leaders. Why is he doing it? They can be as biased as they want, but they’ll show just how bad and how dumb they are if they do.”

Fox News’ Joseph Wulfsohn contributed to this report.