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Senate lawmakers investigating Russian interference in the 2016 presidential election have asked Facebook, Google and Twitter to testify at a Nov. 1 hearing, a source familiar with the matter told Recode on Wednesday.

The inquiry — to be held by the Senate Intelligence Committee — could subject the three tech giants and their executives to uncomfortable questions in the open about the extent to which Kremlin-backed forces may have used their platforms to spread misinformation, and what those companies might have done differently to stop it.

The House Intelligence Committee, meanwhile, plans to drag tech companies to the U.S. Capitol for its own hearing this October, the panel announced Wednesday.

"In the coming month, we will hold an open hearing with representatives from tech companies in order to better understand how Russia used online tools and platforms to sow discord in and influence our election,” said Reps. Mike Conaway and Adam Schiff, the top Republican and Democrat on the committee, respectively.

In their statement, they did not specify a date, or which companies they hoped to grill in October. But a committee aide told Recode they expected Facebook, Google and Twitter to appear at the session.

For now, a spokesman for Facebook confirmed the company had received an invite to appear in the Senate. Spokespeople for Google and Twitter did not immediately respond to requests seeking comment. None of those companies, however, confirmed its attendance.

Lawmakers from both parties have called for a hearing particularly in light of reports that Russian forces purchased 3,000 ads on Facebook in the months before the 2016 election. Some of those ads sought to provoke racial, religious and social tensions in the United States, according to sources who have reviewed them.

So far, Facebook has briefed the committee and its House counterpart on the matter, and Twitter is set to visit Capitol Hill on Thursday to answer lawmakers’ questions. Google briefed the Senate Intelligence Committee earlier this year.

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