Google, Twitter, and Facebook execs have been asked to testify on Russian election meddling before a public Senate Intelligence Committee hearing Nov. 1, Reuters reports.

Citing a Senate aide, the report said representatives from Google and Facebook acknowledged receiving the Senate committee requests, but did not say if they would attend. Twitter had not responded to requests for comment.

Facebook said this month that Russian trolls are suspected of buying more than $100,000 of advertising during the 2016 election in an attempt to sway voters.

Some Congressional Democrats have called for new disclosure rules for online political ads.

President Trump went after Facebook in a tweet Wednesday, accusing the social network of colluding with media outlets opposed to him.