With new attacks by President Donald Trump, high-stakes testimony Sept 5 on Capitol Hill, and a midterm election vulnerable to online manipulation, tech’s giants are bracing themselves for two months after Labor Day that could decide whether and how much the government regulates them. The companies — led by Facebook and Google but with Twitter, Apple, and Amazon also in the mix — are caught in a partisan vise, between privacy-oriented critics on the left who fear further election interference and newer charges from the right of anti-conservative bias and censorship.