WASHINGTON – Social media giants Facebook, Twitter and Google must testify before congressional panels investigating Russian involvement in the 2016 presidential election, according to the top Democrat of a powerful House committee.

“They need to be fully forthcoming,” said Rep. Adam Schiff, the ranking Democrat on the House Intelligence Committee looking into Moscow”s meddling. “And I’m confident they will. I think, frankly, they need to come and testify before congress because there’s a lot we need to know about this.”

The ongoing probes are focusing on how Russian President Vladimir Putin’s cronies used social media – through ads, fake news and manipulating damaging information – to influence the election.

Facebook publicly disclosed that fake accounts tied to Russia bought $100,000 in political ads.

The social media giant turned over copies of the ads and details about the accounts that bought them to the attention of special counsel Robert Mueller.

“The Russians were really aiming to divide us, to sew discord, to effectively set one American against another on some of the most divisive issues that we have,” Schiff (D-Calif.) told ABC’s “This Week.” “All Americans, all patriotic Americans of both parties, ought to be outraged by that. And we need to know the full extent of their use of social media to influence us from Facebook, from Twitter, from Google, from any social media or search engine.”

The bipartisan leaders of the Senate Intelligence Committee – Sen. Richard Burr (R-N.C.) and Sen. Mark Warner (D-Va.) – already signaled their panel would like to hear from Facebook and Twitter officials.

Warner referred to the social media influence in political campaigns as “the wild, wild, West.”