Quid Pro Collusion
Absent a Mueller report or any thorough Congressional investigation so far, I think that a case can be made for collusion (using "collusion" as a sort of umbrella term encompassing about a dozen federal crimes) between the Trump Campaign & Russia - just going by PUBLIC RECORDS.
From statements made from his spokespeople from around the world, from his speeches, from campaign or family emails & his own social media, Trump's aides, allies & associates can be charged under a variety of statutes.
Conspiracy.
Bribery.
Money-laundering.
Aiding & Abetting Computer Crimes.
Wire fraud.
Bank fraud.
Illegal solicitation of foreign donations.
Election fraud.
Perjury.
Making false statements to Congress.
Obstruction.
That's just 11.
Collusion is a meeting of the minds & there have to be steps taken in furtherance of a particular offense. It's more than criminal intent. When the parties have clandestine meetings or agreements with hostile foreign powers - or deliberately connect with foreign agents in Seychelles or in Trump Tower . . . Tick . . . Tick . . . Tick . . .
But then again, collusion technically has to be a meeting of the minds & a case could conceivably be made that Trump is completely out of his.