The Dems knew that with the election of Trump, their crimes would be exposed. Hillary Clinton was once reported to have said that if Trump was elected President that they would all ‘hang from nooses.’
So, they’ve been busy. I think that the Dems have claimed that Trump has committed crimes with the Russians and Ukrainians, these two countries specifically, for two primary purposes:
1 – It allows them to clean up whatever trails they can, however futile an effort that might be. The Democrats have crimes related to both these countries. By ‘investigating’ President Trump for alleged crimes they can poke their noses around every Russian and Ukranian corner with the cover that they are investigating the President, when actually they are tying up loose ends and hopefully get rid of whatever evidence is floating around out there regarding their real crimes.
2 – When it finally comes down on them, they will claim to the American people that Trump is prosecuting them out of revenge for their noble efforts in ‘trying to hold him accountable for his crimes’. They will be able to say that they are being attacked because Trump is being vengeful and they will cling to that story as their ship sinks to the bottom.