There is a misconception that the constitutional phrase ‘high crimes and misdemeanors’ mean whatever Congress wants it to mean.
The Federalist Papers identified high crimes and misdemeanors as “those offenses which proceed from the misconduct of public men, or in other words from the abuse or violation of some public trust. They are of a nature which may with peculiar propriety be denominated political, as they relate chiefly to injuries done immediately to the society itself.”
Public officials may be charged with ‘official misconduct’, which is a violation of the oath of office to follow the law and/or represent the public good.
Interpretation of the concept of ‘high crimes and misdemeanors’ is not subject to political whimsy. The president- and other federal officials- are not ‘at will’ employees who may be removed for any reason or no reason at all.
Should the president be impeached, the Chief Justice of the Supreme Court would preside over the trial. The Chief Justice would be responsible for keeping the proceedings to the intent of the Constitution.
Sadly, the Founders foresaw a time when a future president would violate the public trust by partaking in bribery, treason, and/or high crimes and misdemeanors.