Sen. Mark Warner, D-Va., defended Big Tech companies against accusations of bias on "The Story" Wednesday, but told host Martha MacCallum they should be obligated to remove "knowingly false" information from their platforms.

Lawmakers on the House Judiciary Antitrust Subcommittee grilled the heads of Amazon, Apple, Facebook and Google earlier Wednesday, with Democrats questioning whether the companies violated U.S. antitrust laws and stole from competitors. Republicans, for their part, accused the companies of practicing censorship and bias against conservatives.

"If I were to post something that said ... 'I think cigarettes are great for your health and I encourage everybody that's under 21 to go out and smoke as much as possible,' and you're on a platform that literally reaches hundreds of millions, if not billions of people, I do think there's a responsibility to take these down," Warner said. "When 65 percent of Americans get some or all their news from Facebook and YouTube, shouldn't they have the same kind of responsibility that Fox News has?"

"You're saying they're essentially media companies, and that's not what they say they are," MacCallum shot back.

Section 230 of the Communications Decency Act of 1996 states that "no provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider."

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Warner said he believed Facebook and other tech companies are motivated more by money than any political bias.

"If you look at the highest daily users and sites that are cited the most often on Facebook ... eight out of 10 of those sites that are most [visted] are very conservative sites," he said. "I actually think Facebook doesn't have a bias, conservative or liberal. I think Facebook has a bias toward making money and they'll turn to the right or to the left."

Fox News' Chris Ciaccia, Brian Flood and Andrew O'Reilly contributed to this report.