Manafort, who’s denied getting cash payments, worked with Kremlin-backed Yanukovych for a decade, helping him win presidential elections in 2010 that tilted Ukraine back into Russia’s orbit until the 2014 revolution that ousted him from power. Trump’s been repeatedly accused of adopting positions favorable to Russian President Vladimir Putin by Democratic contender Hillary Clinton’s campaign, which said Tuesday there were “real concerns about the pro-Kremlin interests” of his team after allegations about the payments emerged.

Corruption inquiry

Ukrainian anti-corruption bureau head Artem Sytnyk said Monday there’s no direct proof so far that Manafort received the money, which included reimbursement of expenses and payments for exit polls and foreign observers, and that the investigation is continuing. Yanukovych is in exile in Russia, where he fled after the deadly 2014 street protests.

Manafort said he’s “never received a single ’off-the-books cash payment”’ and that all money directed to him was for work carried out in Ukraine by his political team, according to a statement reported by NBC News on Monday. He hasn’t “ever done work for the governments of Ukraine or Russia,” and his work in Ukraine ended after parliamentary elections there in October 2014, according to the statement.

Manafort has been relying on a former interpreter for Russian military intelligence to collect unpaid fees in Ukraine owed to his company by the Opposition Bloc, a political party founded by former Party of Regions legislators, Politico reported Friday. The aide, Konstantin Kilimnik, began working for Manafort in 2005 and continued to lead his office in Ukraine after Yanukovych fled the country in 2014, it said, citing business records and political operatives that it didn’t identify.

Trump, Putin

Putin has praised Trump as “a colorful person” while the Republican candidate has said the U.S. and Russia could work more closely together under his presidency. Trump said he’d consider recognizing Russia’s 2014 annexation of Crimea, and raised alarm in eastern Europe in July by saying that the U.S. would only defend NATO allies against a possible Russian attack if those nations “have fulfilled their obligations to us.”

Trump campaign officials also removed a platform commitment to provide “lethal defensive weapons” to Ukraine at last month’s Republican party convention, replacing it with a pledge only to provide “appropriate assistance,” the Washington Post reported.

Manafort’s lobbying firm directly orchestrated a covert campaign on behalf of Ukraine’s ruling party to try to sway U.S. public opinion in favor of the country’s pro-Russian government, according to e-mails obtained by the Associated Press. He and his deputy, Rick Gates, never disclosed their work as foreign agents between 2012 and 2014 as required under federal law, the AP said.

The New York Times reported on Monday that Ukrainian anti-corruption investigators were examining ledgers containing references to $12.7 million in undisclosed cash payments to Manafort over a five-year period linked to his work for the Party of Regions.