Ever since reports of a telephone call with Donald Trump emerged last month, the news has been bad for the Ukrainian president, Volodymyr Zelenskiy.

In the space of a few weeks, he has faced protests over a controversial peace deal in Ukraine’s south-east, a lacklustre visit from the IMF and the resignation of a reformist cabinet member.

What was needed, his administration decided, was a grand gesture to recapture the narrative of a young, outsider president with a 70 per cent approval rating.

That gesture came on Thursday, as Ukraine’s president held what his office called a “marathon” press conference lasting more than 14 hours, with 300 journalists in attendance, which looked more like a forced march by the end.

Zelenskiy took questions at Kyiv food market in the refurbished Arsenal weapons factory, where he sat at a broad table next to a stall advertising “oysters and sparkling”.

The venue was carefully chosen to signal the administration’s openness. Eight hours into the event, a man in a vest bearing the word “expert” presented Zelenskiy with an award for holding the world’s longest press conference, an honour previously held by the leader of Belarus.

Over the course of the day, Zelenskiy told shifts of journalists he had not been blackmailed by Trump in their phone call on 25 July and did not know US military aid had been delayed at the time.

A White House summary of the call showed Trump asked Zelenskiy to investigate business dealings by the family of his political rival Joe Biden in Ukraine, as well as claims the former vice-president had a Ukrainian prosecutor fired for looking into a company where his son worked. No evidence has shown Biden was motivated by his son’s work.

Q&A What is the Trump-Ukraine scandal at the heart of impeachment? Show 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

Zelenskiy said he was ready to investigate Ukraine’s role in the 2016 US elections if served with an official request by the US. He also said he knew he had needed to secure a meeting with Trump, saying US relations with Ukraine were “tired” and the Americans “wanted to know where their money had gone”.

But Zelenskiy’s main message to the US was: leave us out of it.

“Choose your own president yourself,” Zelenskiy told American reporters in an attempt to stake neutral ground in a Democratic impeachment inquiry. “And if possible, we ask you not to influence elections in a free Ukraine.”

Down below, journalists ate lunch at stalls with names such as Bali Bowl and Milk Bar as protesters and petitioners occasionally shouted up to Zelenskiy. One, the mother of a Ukrainian lawyer stabbed to death in 2017, demanded a proper investigation into the murder, and justice for her daughter.

Over the hours of questioning, Zelenskiy dodged queries about his relationship with the billionaire Ihor Kolomoisky, and called ending the war with Russian-backed separatists in south-east Ukraine the most important goal of his presidency.

The spectacle recalled a hallmark of another politician: Vladimir Putin’s marathon press conferences and Q&A sessions, controlled but flashy affairs primarily designed to show the Russian president’s transparency without putting him in danger of embarrassing himself.

Zelenskiy also said he would have to meet Putin face to face to end the war, which would be deeply controversial in political circles in Kyiv.

“No one talks about the meeting in person because everyone is against it,” he said. “However, the meeting must be held if we want the war to end.” No date had been discussed, Zelenskiy added.

The event was a tacit rebuttal to journalists who have complained Zelenskiy’s administration has been opaque, and have accused his press secretary of bodychecking or physically pulling them away from the president.

But the effect was not always convincing. In an early round of questioning, Zelenskiy turned on a reporter for the Kyiv magazine Novoye Vremya, asking why a key investor was from the Czech Republic and not a Ukrainian citizen.

“I’ve always said that the mass media should be independent and Ukrainian,” Zelenskiy said in his remarks. The reporter later shot back: “I think it’s better that media is owned by an EU citizen than corrupt oligarchs.”