Rudy Giuliani's quest for dirt on Biden via Ukraine – a timeline

Ed Pilkington in New York
Photograph: Aram Roston/Reuters

7 April

Rudy Giuliani alleges on Fox News that former vice-president Joe Biden was involved while in office in irregular activity in Ukraine. The lawyer claims Biden pressed for the dismissal of a top Ukrainian prosecutor who had been leading a corruption investigation into a gas company on whose board Biden’s son Hunter had served.

Related: Ukraine imbroglio confirms Giuliani's as Trump's most off-kilter advocate

25 April

Biden launches his presidential campaign.

1 May

The New York Times reports that Giuliani has been urging Ukraine to conduct a new investigation into the activities of Joe and Hunter Biden. “Giuliani called Mr Trump excitedly to brief him on his findings,” the paper says.

10 May

Giuliani cancels a trip to Ukraine. He had planned to travel to Kiev to put pressure on President-elect Volodymyr Zelensky to reopen investigations, in the hope of dredging up dirt on the Bidens. The lawyer described the aim of his aborted visit as “meddling in an investigation” and admitted “somebody could say it’s improper”.

20 May

Zelensky assumes the Ukrainian presidency.

25 July

Key telephone call takes place, between Trump and Zelensky. The call now appears to be at the centre of the whistleblower complaint filed the following month.

12 August

Whistleblower complaint is filed by a member of the intelligence community, raising an “urgent concern” relating to the president’s actions.

21 August

Giuliani reveals that in August he travelled to Madrid to meet a top Ukrainian official, Andriy Yermak. He “strongly urged” Yermak to reinvestigate the Bidens, among other matters. “Just investigate the darn things,” Giuliani says he told the official. The lawyer insists he is acting as a “private citizen”, though it later emerges the meeting was arranged with the help of Kurt Volker, US envoy to Ukraine.

9 September

Leading Democrats in Congress write to the White House counsel, Pat Cipollone, requesting all documents relating to any effort by Trump to put pressure on the Ukrainian government to help with his re-election bid. The letter accuses Trump and Giuliani of acting “outside legitimate law enforcement and diplomatic channels” to harm Biden’s campaign.

13 September

Adam Schiff, Democratic chair of the House intelligence committee, subpoenas the Trump administration, demanding that the whistleblower complaint be handed over. Refusal to do so by the director of national intelligence, a Trump appointee, sparks an constitutional tug-of-war.

18 September

The Washington Post reveals that the whistleblower complaint concerns Trump’s “communications with a foreign leader” and a “promise” that was regarded as “troubling”.

19 September

Giuliani is interviewed by Chris Cuomo on CNN and in a heated exchange at first denies that he asked Ukraine to investigate Biden. About 30 seconds later, he reverses himself. “Of course I did,” he says.