What exactly is stopping them? If they have evidence of Trump or anyone else "colluding" with the Russians to rig our election, why wait? Look at the indictments Mueller handed down and what they were for, lying to the FBI over an unrelated matter?? Lies to a House panel on contact with wikileaks? A bunch of Russians who had no links to Trump and who will never be tried. If that is all there is this has been a monumental waste of time and money. Now if Mueller proves Trump has prior knowledge and urged people to lie then he is guilty of conspiracy and obstruction. If he had conversations with Russians to do something to mislead the voting public by using Russian bots in a significant way or rig the voting, then he is guilty of tampering and conspiracy to defraud the American Voters. Let's see what the report actually says and go from there because if he is guilty he should be impeached, if not everyone needs to quit all the theatrics about collusion/conspiracy/obstruction and get on with the peoples business, (that's us). Personally I don't know the Donald and don't owe him any money so I don't care how it turns out but like (supposedly) every other American citizen he deserves the presumption of innocence until found guilty.
Explain to me why the RNC platform was changed to support Russia's takeover of Crimea.
Explain why Trump's Campaign Manager was an employee of a Russia intelligence officer and got away with owing a Russian oligarch/mafioso eight figures?
Explain why Trump's National Security Advisor had been paid to speak to a Russia Today dinner and sat with Putin.
Explain why Kushner wanted to set up secure communications with the Russians at the Russian Embassy so that U.S. Intelligence wouldn't hear what was going on.
Explain why the lies about Trump Tower meeting which was about ending sanctions.
Explain why one of Putin's closest allies paid nearly $40,000,000 over the asking price for Trump's property in FL that had been on the market for months with zero offers? Oh yeah, that guy's private jet was parked next to Trump's at about five campaign stops.
Explain why Putin's personal bank loaned Trump Toronto over $100,000,000 after the property had gone bankrupt. Oh yeah, it's illegal for any American to deal with that bank.
Explain why AG Sessions personally took over a Russian money laundering case from people who lived at Trump Tower and dismissed ALL criminal charges and took less than $6,000,000 as a fine in a $220,000,000 tax fraud and money laundering scheme.
There's plenty more. Why don't you start with those?