WASHINGTON (BLOOMBERG) - President Donald Trump wanted Ukraine's president to make a public statement explicitly tying Joe Biden and Hillary Clinton to a corruption investigation, according to testimony from a State Department official.

Trump "wanted nothing less than President Zelenskiy to go to microphone and say, investigations, Biden and Clinton," State Department official George Kent told House committees conducting an impeachment inquiry, according to a transcript of his Oct 15 testimony that was released Thursday (Nov 7).

When asked if the word "Clinton" was shorthand for 2016, meaning an investigation into the 2016 campaign, Kent said: "2016, yes." Kent didn't have first-hand knowledge of Trump's words. He said he was describing what a colleague told him about a conversation Trump had with US Ambassador to the European Union Gordon Sondland where the demand for Ukrainian President Volodymyr Zelenskiy was outlined.

Kent, the deputy assistant secretary in the State Department's European and Eurasian Bureau, said the Trump administration had two points of leverage for that demand: an Oval Office meeting for the newly elected Ukrainian president and a hold on military aid authorised by Congress.

Kent said he wrote a memo in August noting "concerns that there was an effort to initiate politically motivated prosecutions that were injurious to the rule of law, both Ukraine and the US."

Kent has emerged as a top witness for House Democrats in their impeachment inquiry against Trump. He is already scheduled to be one of the two witnesses in the first open impeachment hearing held by the House Intelligence Committee on Wednesday.

Kent's other main concern was the effort to slander Marie Yovanovitch, then the US ambassador to Ukraine. According to the transcript, Kent said Ukrainian officials used Trump's personal lawyer, Rudy Giuliani, to get "revenge" on Yovanovitch for her anti-corruption work.

Giuliani engaged in a campaign "full of lies and incorrect information" against the ambassador, Kent said. Yovanovitch was abruptly recalled from her post in May.

Kent also described the involvement of Giuliani's business associates, Lev Parnas and Igor Fruman, who subsequently were charged in the US with illegally funnelling hundreds of thousands of dollars to US officials and a political action committee that backed Trump.

Parnas and Fruman "started reaching out actively to undermine Ambassador Yovanovitch, starting in 2018 with a meeting with former Congressman Pete Sessions on May 9th, 2018," Kent said, according to the transcript.

Kent noted that was the same day Parnas and Fruman met with Sessions, the then-House Rules Committee chairman, who "wrote a letter to Secretary Pompeo impugning Ambassador Yovanovitch's loyalty and suggesting that she be removed." "And others also in 2018 were engaged in an effort to undermine her standing by claiming that she was disloyal," Kent told the committees.

Also involved in the effort was the then-prosecutor general of Ukraine, Yuriy Lutsenko, who was under pressure from the US State Department for "essentially colluding with a corrupt official to undermine the investigation" into a ring that was selling fake Ukrainian passports, according to Kent.

Lutsenko "vowed revenge, and provided information" to Giuliani "in hopes that he would spread it and lead to her removal," Kent said, referring to Yovanovitch. He said Ukraine Interior Minister Arsen Avakov told him that Lutsenko had made a private trip to New York to meet with Giuliani "to throw mud" at Yovanovitch and others in the State Department.

Lutsenko resigned under pressure from Ukraine President Volodymyr Zelenskiy in August.

Kent also testified about Acting White House Chief of Staff Mick Mulvaney's designation of a three-person team - Sondland, then-Special Envoy to Ukraine Kurt Volker, and Energy Secretary Rick Perry - to help Giuliani's shadow diplomacy effort. Kent recalled these three came to call themselves as the "three amigos." Sondland was one of the leading figures pushing for Zelenskiy's public statement regarding investigations of Biden and Clinton, according to Kent's testimony.

"I think the anticipation or the hope was that sending that signal would clear the way for both the White House visit as well as the resumption or the clearing of the administrative hold on security assistance," Kent said.

There were indications that the Ukrainians understood what they were being asked to deliver.Kent relayed an account of a mid-September conversation Taylor and Volker had with Andriy Yermak, a top adviser to Zelenskiy. Kent wasn't part of the discussion, but he said Taylor filled him in over breakfast the next day. Volker told Yermak that the US didn't think opening an investigation of former Ukraine President Petro Poroshenko, who Zelenskiy defeated earlier in the year, was appropriate. "And then Andriy Yermak said: 'What? You mean the type of investigations you're pushing for us to do on Biden and Clinton?'" Kent testified. "And at that point Kurt Volker did not respond."

Republicans on the three committees leading the impeachment inquiry highlighted the fact that Kent didn't have firsthand information about Trump's requests, but rather relied on the recollection of people who spoke with him.

"The George Kent transcript was just released & once again there's ZERO 1st hand info of US $ to Ukraine being linked to specific investigations," Representative Lee Zeldin, a New York Republican, tweeted Thursday.