Actually there is a large amonut of circumstantial evidence available to the general public. Of course we don't have anything official from Mueller's investigation yet. Trump will fire Mueller before November in any case, likely very soon now, before Mueller has a chance to subpoena him to appear before a grand jury (its already certain that Trump will refuse to testify except remotely in written response to written questions. Firing Mueller won't stop the investigation , barring something very bizarre from the Republicans. In any case, Mueller's findings will be preserved for the next prosecutor to pick up where Mueller left off. Mueller's firing will just be one more piece of the obstruction pie. When Trump admitted he fired Comey because he was investigating possible election collusion with Russians that was the second pieces of pie. The first piece was when Trump tried to interfere with investigation of Flynn and asked for Cpomey's "loyalty", after clearing the room of witnesses. And of course there is the money laundering and tax fraud shoes yet to drop, and only Mueller's team and God know what else. We have the Nunes report coming out momentarily. To which the House Democrats may have no choice but to respond with the rest of the picture, just as Feinstein was compelled to do when Grassley wouldn't release the testimony before the Senate Committee. Nunes has cherry picked, so I doubt the House Democrats are going to let him get away with it.
Everything will be determined by the November election, either Trump will be protected by Republicans, or he will be impeached depending on the election outcome. If he is impeached, he could be convicted. He could even be indicted later and serve jail time, after Pence is out of office if a Democrat is in the White House.. (I don't think it's possible for Pence to issue a blanket pardon for crimes not yet proven.) So there are manifold possibilities here. Way too soon to draw firm conclusions. . It is going to get very interesting.
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I agree with jem. You can't get "obstruction to stick" without an underlying crime.