Comment by Alyona Getmanchuk for “Financial Times”.

Ben Hall in London and Max Seddon in Moscow

Volodymyr Zelensky’s eagerness to please his US counterpart Donald Trump, as recorded in a transcript of their telephone conversation in July, speaks volumes about Ukraine’s predicament and the delicate balancing act its new president must perform.

Mr Zelensky, a former television comedian who won the presidency in a landslide election victory in April, is determined to bring peace to eastern Ukraine where his armed forces are still fighting Russian-backed separatists. He cannot afford to alienate a US leader who appears to be a lot softer on Russia’s President Vladimir Putin than the rest of his administration.

“You are a great teacher for us,” Mr Zelensky fawned. Mr Trump responded by repeatedly pressing the Ukrainian leader to meet his lawyer and adviser Rudy Giuliani to discuss a fresh investigation in Kiev into whether former US vice-president Joe Biden and his son Hunter conspired to kill off a corruption investigation into a local gas tycoon.

The Ukrainian’s flattery was not enough.

For weeks after the call, Mr Zelensky’s officials fretted to the Financial Times about establishing a “chemistry” between the two former TV personalities. “That’s all that matters,” one official said. “I’m not even worried about any policy outcomes.” Meanwhile, Mr Trump stalled the release of $391m of military aid to Kiev.

With Democrats now vowing to impeach Mr Trump over allegations that Mr Trump was strong-arming a foreign ally to help undermine a potential rival at home, the chemistry between Kiev and Washington threatens to become poisonous at a crucial juncture.

“I’m sorry, but I don’t want to be involved in democratic open elections of the USA,” Mr Zelensky pleaded as he met Mr Trump in New York on Wednesday.

“It is very important to keep good relations with the current president but at the same time crucial to maintain bipartisan support in the US,” said Alyona Getmanchuk, director of the New Europe Centre, a think-tank in Kiev. “Zelensky understands if he supports Trump he loses the Democrats. He’s caught in a trap.”

The Ukrainian response to the allegations against Mr Trump has so far been disciplined circumspection, as officials in Kiev refused to be drawn about the alleged pressure on their president. Mr Zelensky on Wednesday described the July phone call with Mr Trump as “normal”.

“Nobody pushed me,” he added.

“In other words, no pressure,” Mr Trump interjected.

Despite the fresh hopes for peace following Mr Zelensky’s landslide election, the comedian fears a dysfunctional US administration eager to restore relations with Russia, possibly at Kiev’s expense, officials said.

The Ukrainian leader’s grin turned into a grimace when Mr Trump on Wednesday urged him to get together with Vladimir Putin “to solve your problem”, an apparent reference to Russian aggression in eastern Ukraine.

Foreign minister Vadym Prystaiko told the FT before the scandal broke that he hoped Mr Zelensky could use Mr Trump’s eagerness to right things with Mr Putin to Ukraine’s advantage by proposing solutions.

“I can imagine the picture, Trump sitting with Putin, says, ‘Vladimir, please, we have so many other things to cover, and you know, this Ukraine, Congress is all over me, and this Ukrainian diaspora in the United States is sizeable and active and crazy. Can’t we just cut it?’” he said.

Mr Zelensky also believes the US has a moral obligation to protect Ukraine after helping it disarm its nuclear arsenal — then the world’s third-largest — after the collapse of the Soviet Union, Mr Prystaiko added. Ukraine had made “a civilisational choice”, he said. Recommended The FT View The editorial board Ukraine’s new president faces a defining choice

It is not just Mr Zelensky’s hopes for co-ordinated western pressure on Moscow that are at stake but his own reputation as a liberal reformer genuinely committed to cleaning up Ukraine’s corrupt judicial system.

At the root of a possible Trump impeachment is Hunter Biden’s work for a Ukrainian gas tycoon, Mykola Zlochevsky, from 2014-19, a time when his father was overseeing Ukraine policy as US vice-president.

Three consecutive Ukrainian chief prosecutors during this period dropped charges or failed to pursue investigations into Mr Zlochevsky. Mr Trump and Mr Giuliani have repeated claims that one prosecutor did so at the Bidens’ behest. In the view of anti-corruption campaigners in Kiev, the prosecutor in question was removed under pressure from western governments, including the US, for not being vigorous enough.

Ms Getmanchuk, of the New Europe Centre, said if Mr Zelensky were seen to be acquiescing to Mr Trump’s demand it would suggest he was “using the prosecution as a political tool as previous Ukrainian leaders have done”. It may not be as serious as falling out with the US president but it “would be a signal to the Ukrainian people that he is not serious about judicial reform, that he is too vulnerable”.

Mr Zelensky is a political neophyte. But the transcript of his call suggests he was shrewd enough not to offer too much.

“The issue of the investigation of the case is actually the issue of making sure to restore the honesty so we will take care of that and will·work on the investigation of the case,” he replied to the umpteenth request.