In a July 2019 phone call, Trump asked Ukrainian president, Volodymyr Zelenskiy, to mount an investigation of his potential rival for the White House in the 2020 election, Joe Biden, and son Hunter Biden – and also to investigate a conspiracy theory that Ukraine, instead of Russia, was behind foreign tampering in the 2016 election.

Trump framed the requests as a “favor” after he reminded his counterpart that “the United States has been very, very good to Ukraine”. Overshadowing the conversation was the fact that Trump had recently suspended hundreds of millions of dollars in military aid that Congress had approved for Ukraine to defend itself against Russia .

News of the call emerged in a Washington Post report on 18 September that an internal whistleblower complaint, filed in August, involved “communications between Trump and a foreign leader”.

Trump’s attempted dealings in Ukraine caused a scandal in US diplomatic ranks. The Democrats have obtained text messages between top US envoys in Ukraine establishing that diplomats told Zelenskiy that a White House visit to meet Trump was dependent on him making a public statement vowing to investigate Hunter Biden’s company.

Trump does not dispute public accounts of what he said in the call, as established by the whistleblower’s complaint, released on 26 September, and a call summary released by the White House itself.

But Trump and allies have argued that the conversation – “I’ve given you that, now I need this” – was not actually as transactional as it appears to be.

Trump’s personal lawyer, Rudy Giuliani, has pressured Ukraine to smear Biden, and the whistleblower said White House officials had caused records of Trump’s Ukraine call to be moved into a specially restricted computer system. The vice-president, Mike Pence, has acknowledged contacts with Ukrainian officials while claiming to have no knowledge of Trump’s Biden agenda.



On 3 October 2019, Trump even suggested that: “China should start an investigation into the Bidens.”

Unlike when he was a candidate, Trump’s invitations for foreign powers to attack his domestic political opponents now have all the power of the White House behind them. Critics say this is a plain abuse of that power and it undermines US national security because it places Trump’s personal agenda first.

The Trump administration also stands accused of obstruction of Congress for resisting congressional subpoenas for documents and testimony relating to the crisis.

A lot of people – from the whistleblower, to career government officials swept up in the affair, to legal scholars, to Democrats and even some Republicans – believe it’s plausible that the president has committed an impeachable offense.

Tom McCarthy in New York