​Facebook rejected a request from Democratic presidential hopeful Joe Biden to take down an ad from the Trump campaign that accuses the former vice president of corruption in his dealings with Ukraine.

The social media behemoth, in a statement released Tuesday, said its decision was “grounded in Facebook’s fundamental belief in free expression, respect for the democratic process, and belief that in mature democracies with a free press, political speech is already arguably the most scrutinized speech there is.”

Facebook continued to say it doesn’t use “third-party fact-checkers” to examine politicians’ commercials or comments.

The half-minute-long video advertisement released last week by the Trump campaign has also been posted on Twitter and YouTube and claims that Biden offered “Ukraine $1 billion to fire the prosecutor investigating a company affiliated with his son.” There is no evidence that Biden or his son Hunter, who worked for a natural gas firm in Ukraine, did anything wrong.

It has also run on Fox News and MSNBC.

Biden campaign spokesman TJ Ducklo told CNN that the video spreads “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,” Ducklo added.

The ad has been viewed more than 5 million times, according to the New York Times, which first reported on the development.

CNN last week rejected the Trump campaign ad because it did not meet “our advertising standards” and because the “ad makes assertions that have been proven demonstrably false by various news outlets.”

Biden threatened to withhold $1 billion in loan guarantees unless Ukraine got rid of its top prosecutor, Viktor Shokin, who was accused by a number of European nations and the International Monetary Fund of being weak on investigating corruption.

Trump and his allies claim Biden wanted Shokin out of the way because he was looking into Burisma Holdings, the company that employed Hunter.

House Speaker Nancy Pelosi launched an impeachment inquiry into Trump after a whistleblower’s complaint revealed Trump pushed Ukrainian President Volodymyr Zelensky to begin an investigation into the Bidens.