Facebook vice president of global public policy Joel Kaplan and Facebook CEO Mark Zuckerberg leave the Elysee Presidential Palace after a meeting with French President Emmanuel Macron on May 23, 2018 in Paris, France.

Continuing her attacks on Facebook, Sen. Elizabeth Warren, D-Mass., zeroed in on the company's policy chief Joel Kaplan, a former George W. Bush aide.

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Warren, a presidential candidate, mounted her latest strike in a series of tweets Tuesday announcing a plan to clamp down on the "revolving door" between the public and private sector. Warren said Facebook and other large corporations "vacuum up anyone and everyone who leaves one of their government regulators in an obvious effort to leverage their new hire's political connections and use the allure of potential future job offers to extract favorable treatment." Warren's plan would bar "giant corporations, banks, and market-dominant companies from hiring senior government officials for at least four years after they leave public office."

As Warren noted, Facebook is not the only company employing this tactic. Google recently hired former top Department of Homeland Security Official Miles Taylor, whom Buzzfeed News reported "was involved in high-level discussions about immigration enforcement" during the period of the agency's family separation policy, based on emails released through public records requests.

In her tweets, Warren said Facebook's lobbying spend has increased since its hiring of Kaplan.

"Since he was hired, Facebook spent over $71 million on lobbying — nearly 100 times what it had spent before Kaplan joined," Warren tweeted. As Facebook now faces at least three confirmed separate antitrust probes, Warren said "Kaplan is flexing his DC rolodex to help Mark Zuckerbeg wage a closed-door charm offensive with Republican lawmakers."

Facebook declined to comment on Warren's tweets.

Zuckerberg had private meetings with policymakers on both sides of the aisle during a trip to D.C. last month. Among the critics he met with was Sen. Josh Hawley, R-Mo., who has introduced a bill to remove tech's legal immunity from liability for their users' content unless they agree to submit to a third-party audit assessing the so-called political neutrality of their algorithms and content processes.

Kaplan was a strategic hire for Facebook, which has weathered attacks from conservatives who believe the company suppresses their voices due to a liberal slant among employees. People close to Kaplan told The Wall Street Journal that he is not a Trump supporter, but more of a traditional conservative. But his appearance at Justice Brett Kavanaugh's congressional hearing on sexual misconduct allegations last year stirred up Facebook employees who were angered by Kaplan's apparent show of support for the accused judge.

At Kaplan's urging, Facebook halted a project last year that was meant to encourage politically different users to engage in less-hostile ways, according to the Journal. Kaplan reportedly warned the feature could add fuel to claims of conservative bias.

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