That’s why our founders wrote the impeachment clause to be broader than criminal activity. Many crimes are not impeachable (jaywalking, for example). Other activity isn’t necessarily criminal but is obviously a basis for impeachment (not defending the United States against a foreign attack).
For our founders, the touchstone of presidential unfitness to serve was always abuse of the public trust. They viewed the president as having a fiduciary obligation to the American people — just like trustees — and if the president violated that duty, he should be impeached. The first Congress discussed as one of the obvious bases for impeachment the possibility that a president dismissed “meritorious officers.” Or as Charles Black, the greatest scholar of impeachment, once reasoned, if the president announced a policy that he would give pardons to every police officer who killed someone in Washington, D.C., that wouldn’t be criminal but would be obviously impeachable.
Mr. Trump’s administration tried to hide the full whistle-blower complaint by attempting an end-around a federal law that requires that the full report be sent to Congress. His own Justice Department (once again) is working hard to clear him of wrongdoing. This time, the president’s appointees in that department did not even have the veneer of first allowing a special counsel investigation to proceed before trying to undermine its conclusions; they tried to stop the investigation before it even began.