[Keep checking this page throughout the day for updated news and analysis of Zuckerberg’s testimony to Congress.]

Mark Zuckerberg is set to return to Capitol Hill on Wednesday, where the Facebook chief executive will face off against a second panel of congressional lawmakers ready to grill him about the social network’s privacy practices and efforts to combat disinformation, including Russian propaganda.

The hearing — before the House Energy and Commerce Committee — will be Zuckerberg’s second in as many days. On Tuesday, he apologized and defended his company in a rare joint Senate session that lasted nearly five hours.

Driving lawmakers’ scrutiny is the controversy around Cambridge Analytica, a political consultancy tapped by President Trump’s 2016 campaign that improperly accessed the names, “likes” and other personal information of millions of Facebook users. In the wake of its review of the firm’s activities, Facebook also has acknowledged that malicious actors scraped information from the public profiles of practically its entire base, more than 2 billion users.

[ Facebook stores its data in this rural North Carolina town, where the privacy debate is just beginning to catch on ]

The controversy has sparked new calls for regulating the tech giant and its industry peers. In the Senate hearing, Zuckerberg acknowledged that the company “didn’t do enough to prevent these tools from being used for harm as well.”

But his calm demeanor at times appeared to frustrate the panel of 42 senators, who also lobbed questions on everything from diversity to bias against conservative news and views at the 33-year-old billionaire — without extracting many new concessions from him.

Zuckerberg is expected to apologize again on Wednesday during his appearance in front of House representatives, according to prepared testimony. Already, lawmakers there have said the Facebook leader must provide greater clarity as to exactly how Cambridge Analytica obtained data on 87 million users in the first place.

[ 14 years of Mark Zuckerberg saying sorry, not sorry ]

Facebook is “a marvelous innovation, it’s an incredible company, but it’s grown to the point where people have a lot of questions,” said Republican Rep. Greg Walden (Ore.), the chairman of the committee, during a recent interview.

Pointedly, though, congressional interrogators on Tuesday warned a suit-clad Zuckerberg that tough regulation and scrutiny might follow if Facebook failed once again to improve its business practices.

“Unless there are specific rules and regulations enforced by an outside agency, I have no assurance that these kinds of vague commitments are going to produce action,” Democratic Sen. Richard Blumenthal (Conn.) said during the hearing.

“Mr. Zuckerberg, you’ve said you’re sorry. I appreciate the apologies,” added Democratic Sen. Catherine Cortez Masto (Nev.) during later questioning. “But please stop apologizing and make the change.”