Yes, bribery. You don't need to go any further than that. High crimes & misdemeanors relate persons of authority who have special duties, or have sworn an oath, and are not crimes shared by common people.
For example:
If I take a bribe from a customer in return for preferential treatment, no problem.
If I take a bribe while in the role of a special duty, that has sworn an oath, and that bribe violates the oath ... that's impeachable. It doesn't even have to be a "crime" it just has to violate the oath of office.
1. At least one TDS sufferer keeps spouting "12 days early!!!!" So, I'll say "What is September 23rd" for $100.
2. September 11th.
I see what you're angling at, but it really doesn't matter. If the reasons for the delay were legitimate and above-board, there wouldn't be a problem with the delay.
The MOTIVE for the delay is why the President was impeached. Congress was in the dark about the delay, the pentagon was in the dark about the delay, even his own diplomats were in the dark. But Giuliani knew, Mulvaney knew (they do it all the time!!), Sondland knew, and Bolton knew.