If the Democrats - oh, sorry, I mean "the totally unbiased and ideologically pure Robert Mueller" really had the goods on Trump colluding with Russians, they'd want you to know about. It would do nothing but serve their 2018 narrative to have that information available to the public. They'd put it in their ads, mention it on every TV broadcast, and use it as the central plank in their midterm platform. "Elect us, and we'll impeach the Russian conspirator."