Angela Lang/CNET

Elizabeth Warren has taken an attention-getting approach to attacking Facebook's recent announcement that it won't fact-check politicians' posts. She's running an ad on the social network that deliberately contains a falsehood.

"Breaking news: Mark Zuckerberg and Facebook just endorsed Donald Trump for re-election," reads the ad, which Warren also tweeted out Saturday. The ad immediately corrects itself but says it's making a point. "What Zuckerberg *has* done is given Trump free rein to lie on his platform," it says, "and then pay Facebook gobs of money to push out their lies to American voters."

Facebook declined to comment on Warren's protest ad, but pointed us to a company tweet in response: "@ewarren looks like broadcast stations across the country have aired this ad nearly 1,000 times, as required by law. FCC doesn't want broadcast companies censoring candidates' speech. We agree it's better to let voters—not companies—decide." (And Warren tweeted back.)

The White House and President Trump's 2020 campaign didn't immediately responded to a request for comment.

Facebook changed their ads policy to allow politicians to run ads with known lies—explicitly turning the platform into a disinformation-for-profit machine. This week, we decided to see just how far it goes. — Elizabeth Warren (@ewarren) October 12, 2019

Late last month, Facebook said it exempts politicians from its third-party fact-checking process and that that's been the policy for more than a year. The company treats speech from politicians "as newsworthy content that should, as a general rule, be seen and heard," Facebook's vice president of global affairs and communications, Nick Clegg, said at the time.

"We don't believe ... that it's an appropriate role for us to referee political debates and prevent a politician's speech from reaching its audience and being subject to public debate and scrutiny," Clegg added.

Earlier this week, Facebook told Joe Biden's presidential campaign that it wouldn't remove an ad by Trump's reelection campaign despite assertions that the ad contains misinformation about Biden. The 30-second video said Biden had threatened to withhold $1 billion from Ukraine unless officials there fired the prosecutor investigating a company that employed Biden's son.

At the time, Tim Murtaugh, a spokesman for Trump's campaign, said the ads were accurate. But Factcheck.org noted that while Biden did threaten to withhold US money from Ukraine, there's no evidence he did this to help his son, which is what the Facebook ad implied. Factcheck.org also said there's no evidence Biden's son was ever under investigation and that Biden and the US weren't alone in pressuring Ukraine to fire the prosecutor, who was widely seen as corrupt.

Responding to Facebook's refusal to pull the ad, Biden spokesman T.J. Ducklo said at the time that "the spread of objectively false information to influence public opinion poisons the public discourse and chips away at our democracy. It is unacceptable for any social media company to knowingly allow deliberately misleading material to corrupt its platform."

And Warren tweeted then that Facebook was "deliberately allowing a candidate to intentionally lie to the American people."

Warren has called for the breakup of Facebook and other big tech companies, saying in part that they wield too much influence. Other lawmakers have called for Facebook and rival platforms to be regulated as a way of addressing concerns about the spread of fake news, among other things.

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Originally published Oct. 12

Update, Oct. 14: Adds tweet from Facebook.