We learned last week that President Trump asked Ukraine’s president—during a call on July 25, 2019—for a personal political favor intended to smear a potential rival in the 2020 election. He apparently did this while actively blocking military aid to Ukraine, which was at the time and is now under ongoing military attack by Russian forces.
Article I, Section 9, Clause 8 of the United States Constitution prohibits the President from accepting “any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State.”
Article II, Section 4 of the United States Constitution specifies that “The President … shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.”
Both Articles I and II prohibit bribery; both require that the President never receive personal favors or anything of value from a foreign head of state. Trump not only sought emoluments and solicited a bribe; it appears he sought to extort those favors by withholding military aid—which could trigger racketeering charges.
The short story: Trump brazenly sought illegal favors from a foreign head of state, apparently to corrupt the 2020 election process, and in so doing violated the Constitution in specific ways that are outlined as cause for removal from office.
democracy witness 
Respond to Bribery is Cause for Removal from Office – US Constitution