By Deepa Seetharaman and Emily Glazer

For more than a decade as he built Facebook Inc. into a global force, Mark Zuckerberg made it clear he didn't care for politics. Early advisers strained to hold his attention in briefings about D.C. lawmakers, people familiar with the matter say, and he frequently said he would gladly leave the politics to others.

No longer. Mr. Zuckerberg is now an active political operator. He has dined with President Trump, talks regularly with White House senior adviser Jared Kushner, and has pressed lawmakers and officials to scrutinize rivals including TikTok and Apple Inc., people involved in the discussions say.

Mr. Zuckerberg's new political moves are part of an effort to protect his company from pressures that range from antitrust scrutiny on both sides of the Atlantic to criticism of its privacy practices and of its role in disseminating misinformation and conspiracy theories. Facebook is also facing new competitive threats from the likes of ByteDance Ltd.'s TikTok. Forging relationships with political leaders, media personalities and activists is now critical to Facebook's continued primacy in social media.

Mr. Zuckerberg, 36 years old, speaks with conservative thinkers and civil rights groups, and -- after leaving most planning for the 2016 U.S. election to deputies -- he is now playing a hands-on role in setting Facebook's policies for this year's race. Many of those policies, especially those affecting political ads and user posts, have been contentious, eliciting criticism from Republicans and Democrats alike, including President Trump and Democratic presidential nominee Joe Biden, as well as from within the company.

The political controversies haven't appeared to inhibit rapid revenue growth for the company, to more than $70 billion last year, up from less than $28 billion in 2016.

Nick Clegg, a former British deputy prime minister whom Mr. Zuckerberg hired two years ago as global policy and communications chief, said the CEO has been "intimately involved" in deciding to bar new political ads the week before the election.

Mr. Zuckerberg declined to comment.

Just this month, Facebook said it would suspend all political ads after polls close on Election Day and limit posts about poll-watching operations that "use militarized language or suggest that the goal is to intimidate, exert control, or display power." Facebook this past week banned posts denying the Holocaust, reversing its longstanding policy, and said it would block ads that promoted antivaccine messages.

Then on Wednesday, Facebook and Twitter limited sharing of New York Post articles containing allegations about Democratic presidential nominee Joe Biden and his son Hunter that the Biden campaign denied. The New York Post is owned by News Corp, which is also the parent of The Wall Street Journal's publisher, Dow Jones & Co. The Post responded with an editorial condemning the Twitter and Facebook actions and saying that "no one is disputing the veracity" of its reporting.

Mr. Zuckerberg's evolution in many ways tracks Facebook's development from a college-based social network into a central element in the American political system -- and a punching bag for both parties. The intense scrutiny of the social-media giant's influence from all sides during the past four years has made increased political acumen a necessity for its CEO. Facebook's massive reach and focus on free speech have at times made it a super-spreader of falsehoods, hate speech, terrorist propaganda and other posts it struggles to control.

Mr. Zuckerberg has lectured Facebook's broadly left-leaning staff about the need to understand that their user base is more conservative, and defended decisions not to remove posts from Mr. Trump that some employees argue violated Facebook's rules. Mr. Zuckerberg's stance has alienated prominent Democrats and civil-rights activists and has frustrated many inside Facebook -- including, at times, Chief Operating Officer Sheryl Sandberg, people familiar with the dynamics say.

Ms. Sandberg declined to comment.

Mr. Biden's campaign manager last month sent the CEO a letter, reviewed by the Journal, calling Facebook " the nation's foremost propagator of disinformation about the voting process." The Democratic nominee has said he has "never been a big fan of Zuckerberg."

"Any insinuation that Facebook accommodates any one political party over another is simply false," a Facebook spokesman said, adding that Mr. Zuckerberg was the "driving force" behind Facebook's election-integrity and civic-engagement efforts.

"Mark Zuckerberg believes strongly that the company must have rules in place to protect free expression, and that we continue to apply them impartially," the spokesman added. "As CEO, part of his job is to work on policy issues and engage with Democratic and Republican policy makers, as well as other voices from across the political spectrum."

Both the Biden and Trump campaigns continue to advertise heavily on Facebook. The Trump campaign considers Mr. Zuckerberg more of a pragmatist than top executives at other major tech companies, according to a person familiar with the matter. But the campaign also has sharply criticized Facebook's policies. "Just like the rest of the Silicon Valley Mafia, Facebook erroneously believes it is the arbiter of truth and decider of elections," said Samantha Zager, a Trump campaign spokeswoman, adding that tech companies increasingly censor Mr. Trump and conservatives.

Mr. Zuckerberg, who is worth more than $90 billion, has contributed to a handful of Democratic and Republican causes and candidates, according to the Center for Responsive Politics. But some people close to Mr. Zuckerberg say the only party he belongs to is the party of Facebook. The one constant for him over the years has been his broad belief that free expression should be paramount and that Facebook is, on balance, good for the world, according to his public comments and people familiar with his views.

Mr. Zuckerberg's growing political awareness also has shaped his personal giving.

Mr. Zuckerberg and his wife have donated $400 million in personal funds to nonprofits that help fund local governments' election costs such as hiring poll workers, providing personal protective equipment and sharing accurate Election Day information. Conservatives are trying to block those private funds from being used for public costs, and many liberals have criticized the effort as hypocritical given what they view as Facebook's record of allowing users to post disinformation about elections and voting.

People who knew Mr. Zuckerberg at Harvard College, where he co-founded Facebook as a student in 2004, say he could best be described as center-left. In the run-up to the presidential election that year, he worried about the prospect that George W. Bush would be re-elected and closely tracked the race in the final weeks, one of those people said.

But he wasn't particularly political. A few years after Facebook was created, political advisers met with him to understand how his views might shape company policy, according to a person familiar with the matter. The advisers explained the differences among the American political groups, including Democrats and Republicans, and the meeting ended when Mr. Zuckerberg agreed that he was best described as a libertarian, rather than closely aligned with either major American party.

"He was completely apolitical," said Tim Sparapani, a technology lawyer who was Facebook's first public-policy director until 2011 and has been critical of the company. "His political views had to be coaxed out of him."

Facebook's policy team -- headed by Ms. Sandberg, a one-time Clinton administration official who joined Facebook in 2008 -- handled most outreach and relationships with lawmakers in the U.S. and globally. Mr. Zuckerberg started to focus on immigration reform and in 2013 he co-founded a nonprofit, Fwd.US, to pursue that cause.

The hands-off approach changed after Mr. Trump's 2016 election. Mr. Zuckerberg was jolted by criticism that Facebook had failed to stem misleading pseudo-news articles and other disinformation that many of its critics said sharpened divisions among Americans and made the race's rhetoric more toxic than in years past.

"What happened in 2016 casts a long shadow four years later," said Mr. Clegg. "Facebook was accused of being asleep at the wheel," he said, and Mr. Zuckerberg determined that it had to change.

Mr. Zuckerberg publicly presented himself as a work in progress, open to self-reflection and eager to understand other perspectives. In 2017, he completed a listening tour of 30 states, an extended road trip that had the trappings of a political campaign. In April 2018, he testified before Congress for the first time to answer questions about Facebook's data-privacy controls. In 2019, he hosted a series of discussions with academics and other executives about the role of technology in society.

Behind the scenes, Mr. Zuckerberg intensified his focus on making sure Facebook wouldn't be seen as partisan, in part by emphasizing Facebook's support for free speech. Some Democratic officials, concerned about misinformation undermining political discourse, perceived him as growing overly deferential to conservatives, who have generally argued against limits on expression on social media. He started asking more policy-related questions and grew more involved in decisions about controversial content on the platform, including the 2018 decision to remove far-right talk show host Alex Jones's properties from the platform, people familiar with the company say. Mr. Zuckerberg tends to get involved in situations where Facebook's policies aren't clear, Mr. Clegg said, but leaves enforcement to his deputies.

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10-16-20 0914ET