WASHINGTON — Facebook has not been fully transparent with Congress about its recently revealed data leak, said Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, warning that government regulation of the social media giant may be in sight.

“I don’t think Facebook has been fully forthcoming,” Warner, D-Va., said Sunday on “Meet The Press.” “I called out Facebook back in December of ‘16. In the Spring of ’17 I questioned micro-targeting and the use of this really sketchy firm Cambridge Analytica. Early on for most of 2017 they blew that off.”

Facebook has been under increased pressure since news broke that Cambridge Analytica, a firm hired by the Trump campaign during the 2016 election, misused information from millions of Facebook users. Facebook CEO Mark Zuckerberg has apologized and promised a number of reforms, including audits of groups that harbor mass amount of information from their users. He also apologized in full-page ads printed in several major newspapers Sunday.

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"All of these social media companies have said they have no responsibility for any of the content," Warner said. "I think we have to re-look at that. I think in many ways they’re media companies.”

Members of Trump's 2016 campaign have sought to downplay the role Cambridge Analtica played in their victory. Corey Lewandowski, Trump's first campaign manager, said Sunday he never approved their contact while working for Trump.

“They did not work for the campaign when I was the manager,” said Lewandowski, who led the campaign until June 20, 2016. “So we have to be clear about that. They pitched me three times, three times I said no. They did not come to the campaign until after I left.”

Facebook meanwhile has also faced deep scrutiny from lawmakers after it was revealed that Russians were able to purchase and disperse advertisements related to American politics on their platform.

“During the summer [Facebook] acknowledged there was paid advertising, but more importantly, that there were a number of Russian accounts that were fake accounts, spread information that touched 150 million Americans,” Warner added.

Russian use of social media to attempt to influence Americans has been one focus of the committee’s investigation into meddling into the 2016 election.

Zuckerberg has faced calls from members of Congress on both sides of the aisle to appear before numerous committees, as well as calls to appear before other lawmakers elsewhere in the world. He told Recode this week he was “open” to testifying if he felt he was the appropriate person at the company.

Warner repeated his call on Sunday for Zuckerberg to appear before his committee.

"There are solutions, and what I invite Mr. Zuckerburg and others is come help work with us. Congress is not always at the best in terms of cutting-edge technology, they need to work with us so we can try to get it right," the senator added. "I don’t want to out-regulate these companies into oblivion, but I do think people need to have the ability to know whether information they’re receiving is honest, truthful and or at least originates in this country."