President Donald Trump repeatedly urged Ukraine’s president to investigate former Vice President Joe Biden’s son Hunter during a telephone call in July, a new report says.

The Wall Street Journal reported that Trump encouraged Ukraine President Volodymyr Zelensky “about eight times to work with Rudy Giuliani, his personal lawyer, on a probe, according to people familiar with the matter.”

Biden is the current front-runner in the race to win the Democratic presidential nomination.

The White House and the Biden campaign did not immediately respond to requests for comment from CNBC about the Journal report.

The Journal report came amid a widening controversy in Washington over another report by The Washington Post that Trump had been the subject of a complaint by a whistleblower related to a purported promise he had made related to Ukraine in a conversation with a foreign leader.

The Post did not identify who the leader was, but noted that the whistleblower complained two and a half weeks after Trump spoke with newly elected Ukraine President Zelensky.

The Post report came as Trump’s lawyer Giuliani said he had asked Ukraine officials to investigate Joe Biden.

The Journal’s new report came as a top Ukraine official reportedly said that Trump “is looking” for Ukraine officials to investigate business dealings of Biden‘s son in that country in an effort “to discredit” Biden as he seeks the Democratic presidential nomination.

The official, Anton Geraschenko, told The Daily Beast that Ukraine is ready to investigate Hunter Biden’s relationship with a Ukrainian natural company “as soon as there is an official request.

But, he added, “Currently there is no open investigation.”

Geraschenko is a senior adviser to Ukraine’s interior minister, who would be in charge of any investigation of Hunter Biden.

“Clearly, Trump is now looking for kompromat to discredit his opponent Biden, to take revenge for his friend Paul Manafort, who is serving seven years in prison,” Geraschenko told The Daily Beast.

Kompromat is a Russian word that means “compromising material.”

Manafort served for several months in 2016 as the Republican Trump’s presidential campaign manager, and is now in federal prison for multiple crimes related to his consulting work for a pro-Russian political party in Ukraine.

His tenure with the Trump campaign ended in August 2016 after a New York Times report that $12.7 million in secret payments earmarked for him were recorded in ledgers of that Ukraine Party of Regions.

Manafort eventually was prosecuted by special counsel Robert Mueller as part of Mueller’s wide-ranging probe into Russian interference in the election that year.

Giuliani for months has been pushing investigations in Ukraine related to two different issues in Ukraine, and has continued to do so as questions about the whistleblower has roiled Congress.

Giuliani’s pressure in turn led House Democrats earlier in September to ask Trump’s White House counsel for all records relating to efforts “to coerce the Ukrainian government into pursuing two politically motivated investigations under the guise of anti-corruption activity.”

“The first is a prosecution of Ukrainians who provided key evidence against Mr. Trump’s convicted campaign manager Paul Manafort,” three top House Democrats wrote White House Counsel Pat Cipollone. “That investigation aims to undercut the Mueller Report’s overwhelming evidence that Russia interfered in the 2016 election to support Trump’s campaign.”

“The other case targets the son of [Joe Biden], who is challenging Mr. Trump for the presidency in 2020.”

Giuliani on Thursday night said on CNN was “a tremendous amount of collusion between Ukrainan officials” and then-Democratic presidential nominee Hillary Clinton, and the Democratic National Committee in 2016, when Clinton was facing Trump in the race for the White House. 

Giuliani told CNN host Christ Cuomo that purported collusion included what he claimed was “a completely fraudulent document” — the pro-Russia Ukraine political parties ledgers — “in order to begin the investigation of Manafort.”

The former New York City mayor also claimed that he has obtained sworn statements from “five people in the Ukraine, who said that ‘we were brought into the White House, the Obama White House, and we were told, ‘Go dig up dirt on Trump and Manafort in January of 2016.’ “

Giuliani has not produced evidence of that alleged collusion.

In the same interview with Cuomo, during which he was highly agitated, Giuliani said that as he was investigation the supposed plot against Manafort, “I found out this incredible story about Joe Biden that he bribed the president of the Ukraine in order to fire a prosecutor who was investigating his son.”

In May, The New York Times reported that Biden, while vice presient, had in March 2016 during a visit to the Ukraine capitol Kiev threatened to withhold $1 billion in American loan guarantees of the nation’s leaders did not fire Ukraine’s top prosecutor, “who had been accused of turning a blind eye to corruption in his own office and among the political elite.”

The prosecutor was booted by Ukraine’s parliament. At the time he was dismissed, The Times noted, the prosecutor was investigating the Ukraine gas company Burisma Holdings, whose board members included Biden’s son, Hunter.

Hunter Biden has said “I have had no role whatsoever in relation to any investigation of Burisma, or any of its officers.”

“I explicitly limited my role to focus on corporate governance best practices to facilitate Burisma’s desire to expand globally,” said Hunter, who left Burisma’s board earlier this year.

The ousted prosecutor has been quoted in media reports as saying he was booted because her was investigating payments to Hunter from the company.

The Washington Post’s editorial board in early September suggested that Trump himself was withholding military aid to Ukraine as part of the effort to pressure that country to probe Joe and Hunter Biden.

“Trump associates want the Ukrainian government to prove that Ukraine improperly acted against Mr. Trump in the 2016 election; but they also want it to meddle in his favor for 2020,” The Post’s editorial board wrote.

The Trump administration released $250 million in military aid to Ukraine on Sept. 12, a week after that editorial ran, and after Republican and Democratic lawmakers raised concerns about the delay in releasing that money, which had been approved by Congress.