Let’s imagine that after the midterm elections of 2018, there is a majority in the House of Representatives (218 congresspeople) who vote for the impeachment of President Trump. Combination of all Dems and a few never-Trumpers in the Republican Party. There will then be a trial before the 100 (99 without the Honorable John McCain) members of the US Senate with the Chief Justice of the Supreme Court presiding. In this hypothetical case the prosecution would have to present actual evidence before the Senate body conforming to the articles of impeachment.
Is there any evidence? His foes claim to have evidence but cannot reveal it on national security grounds. True, several people close to him have been indicted on financial irregularity charges which however predate his administration. Actual evidence would have to be presented. Meeting with a foreign leader in private might not be grounds. Every President has done this. There was no screaming of treason when he met with Kim Jong Un, a foreign leader who threatened to nuke the US.
What would the prosecutor’s case be based upon other than emotion?