UPDATED with details about Senate testimony: Facebook CEO Mark Zuckerberg will appear before House and Senate committees next week to answer questions about the Cambridge Analytica scandal, even as it disclosed today that the political consulting firm connected to President Donald Trump’s 2016 election might have accessed more user data than originally thought.

Zuckerberg will testify before a joint session of the Senate Judiciary and Commerce Committees on April 10, then appear the next day before the House Energy and Commerce Committee, answering growing questions about data privacy and how Facebook plans to address the problem.

“Social media has revolutionized the way we communicate, using data to connect people from around the world,” said Judiciary Committee Chairman Chuck Grassley (R-Iowa). “With all the data exchanged over Facebook and other platforms, uses deserve to know how their information is stored and secured.”

In an effort to appear more forthcoming about data leaks, Zuckerberg held a question-and-answer session today with reporters, where he revealed that Cambridge Analytica might have harvested the data of up to 87 million users — substantially more than the 50 million initially reported. The social network, which has announced a crackdown on third-party apps gathering data on users, acknowledged that the public profiles of its 2 billion users might have been collected without their knowledge or permission.

CNN first reported that Facebook’s co-founder would testify — and hoped to drag Google CEO Sundar Pichai and Twitter CEO Jack Dorsey with him into the public spotlight. A Facebook spokesperson initially declined to confirm the report.

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Grassley last week called on the three tech executives to appear before an April 10 data-privacy hearing to discuss past and future policies regarding the protection and monitoring of consumer data. Other legislators have been urging Zuckerberg to travel to Washington, D.C., to address answer questions.

Facebook has been buffeted for a week by reports that the political consulting firm Cambridge Analytica used data harvested from 50 million Facebook users, without their knowledge or consent, to influence the 2016 presidential election. The firm, which advised Donald Trump’s campaign, repeatedly has denied these claims.

The social media giant has embarked on a campaign to restore users’ confidence in the platform in the wake of these damaging revelations, with Zuckerberg and COO Sheryl Sandberg granting media interviews and issuing statements intended to reassure users that Facebook will safeguard their data.

Meanwhile, prominent tech figures including WhatsApp co-founder Bryan Acton urged users to vote with their clicks and DeleteFacebook.

Elon Musk followed suit, deactivating the Facebook pages for two companies he leads, Tesla and SpaceX, and declaring publicly that the social media platform “gives me the willies.”

Technology analyst Daniel Ives of GBH Insights called Zuckerberg’s decision a step in the right direction, saying it will help calm the public.

“While this will not be a pleasant experience for Zuckerberg and his team going in front of Congress, it is a necessary smart strategic step for Facebook to head to the Beltway as the public fury continues to grow around the Cambridge data leak which represents the darkest chapter in the company’s 14 year history,” Ives wrote.