Sen. Mark Warner said Facebook was slow to react to Russian manipulation of its social media platform during the 2016 presidential election.

The Virginia Senator is the top Democrat on the Senate Intelligence Committee, which has been investigating Russian meddling in the 2016 elections, said Facebook initially “blew off” this threat.

“They were slow to the game,” Warner said in remarks this morning at the Code Conference in Rancho Palos Verdes.

Warner said Facebook’s promises to provide greater transparency around campaign ads on the site doesn’t go far enough to address the problem that was exposed in the wake of the elections, in which some 150 million Facebook users encountered inflammatory posts created by a Russian propaganda operation.

“That’s not where the rubber hits the road,” Warner said. “Where the rubber hits the road is misinformation.”

Warner said Facebook continues to chase fake accounts that are used to spread spurious information. The social network said it has disabled about 583 million fake accounts during the first three months of this year — the majority of which, it said, were blocked within minutes of registration.

The Senator urged the social media platforms to work with legislators to address these larger questions about identity and misinformation.

“I’m trying to reach out to the platform companies to say, ‘Work with us,'” said Warner. “If you leave it to Congress, they’ll screw it up.”

Warner hit on a number of other topics during his comments, from the urgency of securing voting systems ahead of the 2020 general elections, to his concern about the president’s repeated attacks on Special Counsel Robert Mueller (“these are not the actions of someone who has nothing to hide.”), to his worries about the public’s fatigue if the Russia probe doesn’t wrap up by the end of the year. Oh, and in case you’re running about his interest in running for president in 2020 the answer is “no.”