His widely-anticipated testimony comes after the social media company revealed Cambridge Analytica, a data firm associated with President Donald Trump's campaign, may have had data on 87 million of its users. The information came to light as questions continue over Russia's meddling in the 2016 election.
To address concerns about fake content, Facebook announced a big set of changes Friday, saying it will now label all political and issue ads, and showing who paid for them, and it will require anyone who wants to run a political or issue ad to verify their identity and location.
While Zuckerberg has taken questions in recent weeks from news outlets, including CNN, his testimony before Congress will put the embattled CEO in a higher pressure setting with lawmakers expected to grill him for hours, with Russian meddling as a major underlying topic.
A source familiar with the matter says Zuckerberg is meeting Monday with lawmakers, including members of committees that are holding his hearings. The office of Florida Democratic Sen. Bill Nelson said that he'd be among those lawmakers meeting with Zuckerberg on Monday.
Trump actions, Cabinet issues overshadow tax message
Zuckerberg's high-profile hearings may draw attention away from what congressional Republicans hoped to focus on this month: the tax law they passed that they believe is the kind of major accomplishment that should convince voters to keep them in the majority. GOP leaders plan to tout the tax cuts around the April 15 filing deadline and hammer home to voters that Democrats never would have delivered that type of paycheck relief if they were in charge.
Many Republicans are deeply concerned about losing one or both chambers in the midterm elections and think the continued focus on what happened in the 2016 election -- and the many other controversies related to the Trump White House -- won't help them win in 2018. The GOP faces stiff winds in November, Senate Majority Leader Mitch McConnell warned last week.
"This is going to be a challenging election year," McConnell said in an interview with Kentucky Today. "We know the wind is going to be in our face. We don't know whether it's going to be a Category 3, 4 or 5."
And Facebook isn't the only issue keeping the focus off tax cuts. While lawmakers were back home, Trump unexpectedly announced several hot-button but unformed policies -- including potentially pulling US troops from Syria after feeling frustrated with the mission and sending the National Guard to defend the border with Mexico -- that Republicans will be forced to walk away from or defend.
In addition, the Cabinet woes facing the White House are landing in the Senate's lap, which now must set aside its business to deal with replacing several key senior executives who were in office for just about a year. While the current legislative agenda is light, McConnell proudly is filling floor time with votes on conservative judicial nominees who are reshaping the courts.
Republicans are openly frustrated they now must devote so much time, attention and political capital to confirming a new secretary of state, CIA director, and Veterans Affairs secretary. The also acknowledge that each of those nominees -- Mike Pompeo, Gina Haspel and Dr. Ronny Jackson -- have faced criticism and may not get confirmed. Upcoming hearings on these critical members of the President's Cabinet will give Democrats the chance to grill them on controversial policies, and expose the divisions inside the President's own party on national security issues.