Sen. Elizabeth Warren (D-MA) on Tuesday morning tore into Facebook following a report containing leaked audio from the company’s top executive and founder.

Facebook CEO Mark Zuckerberg addressed a question about Warren’s plan to break up big tech companies during an internal Q&A session and expressed concern about the prospect. According to the leaked audio, obtained by The Verge, the social-media titan said: “If she gets elected president, then I would bet that we will have a legal challenge, and I would bet that we will win the legal challenge. And does that still suck for us? Yeah. I mean, I don’t want to have a major lawsuit against our own government.”

Zuckerberg added, according to the audio: “But look, at the end of the day, if someone’s going to try to threaten something that existential, you go to the mat and you fight.”

Warren responded on Twitter by saying: “What would really ‘suck’ is if we don’t fix a corrupt system that lets giant companies like Facebook engage in illegal anticompetitive practices, stomp on consumer privacy rights, and repeatedly fumble their responsibility to protect our democracy.”

In a subsequent Facebook post, Zuckerberg confirmed the authenticity of the audio: “Even though it was meant to be internal rather than public, now that it’s out there, you can check it out if you're interested in seeing an unfiltered version of what I'm thinking and telling employees on a bunch of topics.”

At issue is a sweeping proposal Warren introduced in March to break up major tech companies like Facebook, Amazon and Google. The plan from the Massachusetts Democrat entailed unwinding major mergers like Amazon’s ownership of Whole Foods and Zappos, Facebook’s ownership of WhatsApp and Instagram, and Google’s ownership of Waze, Nest, and DoubleClick as well as requiring companies with an annual global revenue of $25 billion and more to be designated as “platform utilities,” subject to new regulations and restrictions.

The social-media giant specifically has become the target of ire among many Democratic presidential candidates, for its misuse of data and allowance for a Russian disinformation campaign on the platform during the 2016 presidential election.