Last month, a friend of the wealthy conservative donor Rebekah Mercer arrived at Facebook’s Silicon Valley headquarters. His task: Find out what — if anything — could repair relations between Facebook, the world’s biggest social media company, and Cambridge Analytica, the voter-profiling firm co-founded by her father and used by the Trump campaign.
The revelation last month that Cambridge Analytica improperly acquired the private Facebook data of millions of users has set off government inquiries in Washington and London, plunging Facebook into crisis. But it has also battered the nascent political network overseen by Ms. Mercer, 44, and financed by her father, Robert Mercer, 71, a hard-line conservative billionaire.
Ms. Mercer’s standing in Mr. Trump’s circle had already declined following the departure last year of Stephen K. Bannon, her family’s former adviser and President Trump’s former chief strategist, according to Republicans with close ties to the president’s political operation. A pro-Trump advocacy group controlled by Ms. Mercer has gone silent following strategic disputes between her and other top donors. Plans to wage a civil war against the Republican establishment in the 2018 midterms have been derailed.
And last month, after reports on Cambridge in The New York Times, The Observer of London and The Guardian, Facebook banned the company from its platform, a major blow to any political or commercial targeting firm. Not a single American candidate or “super PAC” committee has reported payments to the company since the 2016 campaign, according to federal records.
Several Republicans in Ms. Mercer’s orbit or with knowledge of Cambridge’s business said that fallout from the Facebook scandal — combined with widespread doubts about the accuracy of Cambridge’s psychological profiles of voters — had effectively crippled the firm’s election work in the United States.
“They’re selling magic in a bottle,” said Matt Braynard, who worked alongside Cambridge on the Trump campaign, for which he served as the director of data and strategy, and now runs Look Ahead America, a group seeking to turn out disaffected rural and blue-collar voters. “And they’re becoming toxic.”
The Mercers have made no public statements about Cambridge Analytica’s troubles. Through a spokeswoman, Ms. Mercer declined to answer questions about her role in Mr. Trump’s circle or the Facebook meeting about Cambridge Analytica.
But the effort by Ms. Mercer’s friend to help mend fences with Facebook hints at both Cambridge’s importance to her family’s political ambitions and the perils posed by Facebook’s ban.
Although a Cambridge spokesman last month downplayed Ms. Mercer’s role at the company — saying she had a “broad business oversight” role and no involvement in its daily operations — she serves on the company’s board and in the past has worked to drum up campaign business for Cambridge, according to Republicans who have worked with or competed against the firm. Former Cambridge employees said she was close to Alexander Nix, the company’s chief executive, who was suspended last month after reports on Cambridge’s harvesting of Facebook data.
Ms. Mercer’s intermediary with Facebook was Matthew Michelsen, a tech entrepreneur and investor based in San Diego, who lists his employer as GothamAlpha, a consulting firm. According to his LinkedIn profile, he has also advised major Silicon Valley companies, including Facebook and Palantir, a data-mining firm and intelligence contractor.
Mr. Michelsen’s meeting came on March 20, the day after Facebook announced that Cambridge had agreed to let it audit the firm’s computer servers. Mr. Michelsen met informally with a Facebook acquaintance who was accompanied by a Facebook lawyer, according to a person briefed on the meeting, and both Cambridge Analytica and the Mercers were discussed. The person discussed the meeting on the condition of anonymity because he was not authorized to speak about it publicly. No immediate actions were taken as a result of Mr. Michelsen’s outreach.
Mr. Michelsen acknowledged in an interview on Thursday that he visited the company but he would not discuss the purpose of the trip, citing nondisclosure agreements Facebook required him to sign. Ms. Mercer declined to say whether she and Mr. Michelsen had discussed the purpose of the meeting or whether he had briefed her on it afterward.
Cambridge also mounted a more formal effort to assuage Facebook, the person said, sending its own lawyers to meet with Facebook on the same day Mr. Michelsen was there. The Cambridge lawyers asked Facebook officials whether the firm could be reinstated on the platform. Mark Zuckerberg, Facebook’s chief executive, acknowledged that meeting in an interview with The Times last month, saying that his company had not decided whether to lift the ban.
A Cambridge spokesman did not respond to requests for comment. In a lengthy public statement on Monday, the company stated that “the vast majority of our business is commercial rather than political, contrary to the way some of the media has portrayed us.”
In recent years, the Mercers have become among the most prominent and highly scrutinized political donors in the…