For years, Serhiy Leshchenko, a top Ukrainian anti-corruption campaigner, worked to expose kleptocracy under former president Viktor Yanukovich. Now, he is focusing on a new perceived pro-Russian threat to Ukraine: US presidential candidate Donald Trump.

The prospect of Mr Trump, who has praised Ukraine’s arch-enemy Vladimir Putin, becoming leader of the country’s biggest ally has spurred not just Mr Leshchenko but Kiev’s wider political leadership to do something they would never have attempted before: intervene, however indirectly, in a US election.

Mr Leshchenko and Ukraine’s anti-corruption bureau published a secret ledger this month that authorities claim show millions of dollars of off-the-book cash payments to Paul Manafort, Mr Trump’s campaign director, while he was advising Mr Yanukovich’s Regions party from 2005.

Mr Manafort, who vigorously denies wrongdoing, subsequently resigned from his campaign role. But Mr Leshchenko and other political actors in Kiev say they will continue their efforts to prevent a candidate — who recently suggested Russia might keep Crimea, which it annexed two years ago — from reaching the summit of American political power.

“A Trump presidency would change the pro-Ukrainian agenda in American foreign policy,” Mr Leshchenko, an investigative journalist turned MP, told the Financial Times. “For me it was important to show not only the corruption aspect, but that he is [a] pro-Russian candidate who can break the geopolitical balance in the world.”

Mr Trump’s rise has led to a new cleavage in Ukraine’s political establishment. Hillary Clinton, the Democratic nominee, is backed by the pro-western government that took power after Mr Yanukovich was ousted by street protests in 2014. The former Yanukovich camp, its public support sharply diminished, leans towards Mr Trump.

If the Republican candidate loses in November, some observers suggest Kiev’s actions may have played at least a small role.

It was important to show not only the corruption aspect, but that [Trump] is [a] pro-Russian candidate who can break the geopolitical balance in the world

“Ukraine’s anti-corruption activists have probably saved the Western world,” Anton Shekhovtsov, a western-based academic specialising in Russia and Ukraine, tweeted after Mr Manafort resigned.

Concerns about Mr Trump rocketed in Kiev when he hinted some weeks ago he might recognise Russia’s claim to Crimea, suggesting “the people of Crimea, from what I’ve heard, would rather be with Russia than where they were”.

Natalie Jaresko, a US-born Ukrainian and former State Department official who served for a year as Ukraine’s finance minister, fired off a volley of tweets to US officials. In one, she challenged former Republican presidential candidate John McCain: “Please assure us you disagree with statement on Crimea/Ukraine. Trump’s lies not position of free world, inc Rep party.”

On Facebook, Arseny Yatseniuk, the former prime minister, warned that Mr Trump had “challenged the very values of the free world”. Arsen Avakov, interior minister, called the candidate’s statement the “diagnosis of a dangerous marginal”.

Ukrainian politicians were also angered by the Trump team’s alleged role in removing a reference to providing arms to Kiev from the Republican party platform at its July convention.

Adrian Karatnycky, a senior fellow at Washington’s Atlantic Council think-tank, said it was “no wonder that some key Ukrainian political figures are getting involved to an unprecedented degree in trying to weaken the Trump bandwagon”.

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Kiev moved beyond verbal criticism when Ukraine’s national anti-corruption bureau and Mr Leshchenko — who has a reputation for being close to the bureau — published the ledger showing alleged payments to Mr Manafort last week.

The revelations provoked fury among former Regions party backers. Asked by telephone about Mr Manafort’s activities in Ukraine, a former Yanukovich loyalist now playing a lead role in the Regions party’s successor, called Opposition Bloc, let loose a string of expletives. He accused western media of “working in the interests of Hillary Clinton by trying to bring down Trump”.

Though most Ukrainians are disillusioned with the country’s current leadership for stalled reforms and lacklustre anti-corruption efforts, Mr Leshchenko said events of the past two years had locked Ukraine on to a pro-western course. The majority of Ukraine’s politicians, he added, are “on Hillary Clinton’s side”.

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