Mark Warner: the tech-savvy senator taking Silicon Valley to task

As executives from Facebook, Google and Twitter prepare to testify on Capitol Hill, one Democrat has emerged as a formidable critic Last month, Senator Mark Warner left a closed-door briefing with Twitter visibly frustrated. He said he doubted whether the tech titan grasped the gravity of the investigation into Russian election meddling, and fumed to reporters that the company’s presentation to congressional investigators about how Russia used its platform to influence the 2016 race was &l