Here is why Trump's actions are impeachable.

[Kablooie]

Suppose a president recieved information that his political rival may have committed a crime in a foreign country.

To allow his campaign committee to investigate, would be okay.

To ask the foreign country's head to investigate might be okay if the crime was likely to have compromised national security.

To ask the foreign country's head to investigate while knowing that a serious crime had not been committed would be totally unacceptable.

To threaten to withhold aid that Congress had approved unless an investigation into an imaginary crime was announced, is impeachable.