From "Intelligencer" - "The most interesting and newsworthy portion of Robert Mueller’s six hours of testimony before the House yesterday came in the final two exchanges of the day, long after the narrative was set and the national media had grown bored. In those ten minutes, Mueller confirmed that Russia had blackmail leverage over Donald Trump during the 2016 campaign."
It's true. Mueller was forced to state under oath, that Russia has blackmail material on Trump.
https://nymag.com/intelligencer/2019/07/mueller-testifies-russia-blackmail-leverage-trump.html
