Sen. Bernie Sanders, the 2020 Democratic frontrunner, suggested Russian President Vladimir Putin is behind "ugly" online attacks often attributed to Sanders' supporters.

The Washington Post reported on Friday that the Russian government is attempting to interfere in the Democratic primary to aid Sanders.

"Some of the ugly stuff on the internet attributed to our campaign may well not be coming from real supporters," he said.

An election-security official from the Office of the Director of National Intelligence told lawmakers in a classified briefing that the Russians are also working to help President Donald Trump get reelected.

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Sen. Bernie Sanders, the 2020 Democratic frontrunner, suggested Russian President Vladimir Putin is behind "ugly" online attacks often blamed on his supporters after The Washington Post's Friday report that the Russian government is attempting to interfere in the Democratic primary to aid Sanders.

Sanders released a lengthy statement condemning the interference on Friday afternoon.

"Unlike Donald Trump, I do not consider Vladimir Putin a good friend. He is an autocratic thug who is attempting to destroy democracy and crush dissent in Russia," Sanders said in the emailed statement. "Let's be clear, the Russians want to undermine American democracy by dividing us up and, unlike the current president, I stand firmly against their efforts, and any other foreign power that wants to interfere in our election."

Notably, the Vermont lawmaker suggested that Putin may also be behind the attacks on other Democrats made by apparent Sanders supporters online in recent days.

"Some of the ugly stuff on the internet attributed to our campaign may well not be coming from real supporters," he said.

Sanders added, "I don't care, frankly, who Putin wants to be president. My message to Putin is clear: Stay out of American elections, and as president I will make sure that you do."

The revelation comes after an election-security official from the Office of the Director of National Intelligence told lawmakers in a classified briefing that the Russians are also working to help President Donald Trump get reelected.

According to The Post, Trump and congressional lawmakers were also informed of Russia's campaign to help Sanders clinch the Democratic nomination, but the type and scope of the Kremlin's interference are still unclear.

The president has so far either refused to acknowledge Russia's meddling or offered a lukewarm condemnation.

Sonam Sheth contributed to this report.