One thing to keep in mind. There’s little doubt that what the President appears to have done counts as within the scope of the constitution’s “high crimes and misdemeanors.” But it may go beyond that. The constitution actually says that the President “shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.”
“Bribery” doesn’t get mentioned a lot. We tend to think of it as the President receiving bribes. But it is not so restricted. And what Trump and Giuliani were up to with Zelensky seems to fit fairly well within federal bribery statutes. Of course, for impeachment, it doesn’t need to fit within the statutes. But impeachment for bribery as well as other high crimes and misdemeanors seems plausible here.
For Giuliani, federal bribery and extortion charges seem plausible, among other infractions.