Sen. Mark Warner Mark Robert WarnerIntelligence chief says Congress will get some in-person election security briefings Overnight Defense: Trump hosts Israel, UAE, Bahrain for historic signing l Air Force reveals it secretly built and flew new fighter jet l Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' House approves bill to secure internet-connected federal devices against cyber threats MORE (Va.), the top Democrat on the Senate Intelligence Committee, accused President Trump on Wednesday of getting in the way of efforts to combat Russian influence operations in the U.S.

During a hearing in which Facebook, Google and Twitter testified before the Senate panel, Warner took the companies to task for failing to detect the foreign interference campaign, before turning his sights on the White House.

"It is not just the platforms that need to do more," Warner said in his opening statement. "The U.S. government has thus far proven incapable of adapting to meet this 21st century challenge. Unfortunately, I believe this effort is suffering, in part, because of a lack of leadership at the top."

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"We have a president who remains unwilling to acknowledge the threat that Russia poses to our democracy," he continued. "President Trump should stop actively delegitimizing American journalism and acknowledge and address this real threat posed by Russian propaganda."

Warner also called on Congress to take up the Honest Ads Act, a bill that he introduced last month with Sens. Amy Klobuchar Amy KlobucharThe Hill's Morning Report - Sponsored by The Air Line Pilots Association - White House moves closer to Pelosi on virus relief bill EPA delivers win for ethanol industry angered by waivers to refiners It's time for newspapers to stop endorsing presidential candidates MORE (D-Minn.) and John McCain John Sidney McCainMcSally says current Senate should vote on Trump nominee Say what you will about the presidential candidates, as long as it isn't 'They're too old' The electoral reality that the media ignores MORE (R-Ariz.) that would subject online political ads to tougher transparency rules like the ones that govern traditional media.

The bill and Tuesday's hearing come after the three social media giants have admitted to selling political ads to a Russian "troll farm" that was aiming to influence last year's presidential campaign.