Article 2, Impeachment of Nixon: "He misused the Federal Bureau of Investigation, the Secret Service, and other executive personnel, in violation or disregard of the constitutional rights of citizens, by directing or authorizing such agencies or personnel to conduct or continue electronic surveillance or other investigations for purposes unrelated to national security, the enforcement of laws, or any other lawful function of his office"

Trump, just prior to his departure on this trip, stood on the White House lawn and directed the Justice Department to investigate Clinton. That was an impeachable offense.