Washington, Nov 21 (AP) Key impeachment witnesses said Thursday it was clear that Donald Trump's personal lawyer Rudy Giuliani was pursuing political investigations of Democrats in Ukraine at Trump's direction.

Their testimony undercuts the president's argument he only wanted to root out Ukrainian corruption.

State Department official David Holmes said he understood that Giuliani's push to investigate "Burisma," the Ukraine gas company where Joe Biden's son Hunter served on the board, was code for the former vice president and his family.

Former White House adviser Fiona Hill warned that Giuliani had been making "explosive" and "incendiary" claims.

"He was clearly pushing forward issues and ideas that would, you know, probably come back to haunt us and in fact," Hill testified.

"I think that's where we are today."

Testimony from Hill and Holmes capped an intense week in the historic inquiry.

The House probe focuses on allegations that Trump sought investigations of Joe Biden and his son — and the discredited idea that Ukraine rather than Russia interfered in the 2016 US election — in return for US military aid that Ukraine needed to fend off Russian aggression, and for a White House visit the new Ukrainian president wanted that would demonstrate his backing from the West.

Hill a former White House Russia analyst, sternly warned Republican lawmakers — and implicitly Trump — to quit pushing the "fictional" Ukraine-interference narrative as they defend Trump in the impeachment inquiry.

Holmes, a late addition to the schedule, testified that he came forward after overhearing Trump ask about "investigations" during a "colorful" phone call with Ambassador Gordon Sondland at a Kyiv restaurant this summer.

Holmes said he realized his firsthand account of what he heard would be relevant.

"Those events potentially bore on the question of whether the president did, in fact, have knowledge that those senior officials were using the levers of our diplomatic power" to push Ukraine to investigate his rivals, he testified.

As Holmes was delivering opening remarks, explaining how the ambassador "winced," holding the cellphone away from his ear because the president was talking so loudly, Trump tried to undercut the career diplomat's account of overhearing the conversation.

The president tweeted that while his own hearing is "great" he's never been able to understand another person's conversation that wasn't on speaker. "Try it," he suggested.

Holmes also testified about his growing concern as Giuliani, the president's personal lawyer, orchestrated Ukraine policy outside official diplomatic channels. It was a concern shared by others, he testified.

"My recollection is that Ambassador Sondland stated, "Every time Rudy gets involved he goes and f---s everything up."

The president instructed his top diplomats to work with Giuliani, who was publicly pursuing investigations into Democrats, according to Sondland and others testifying during the week of blockbuster public hearings.

Holmes testified that he grew alarmed, watching as Giuliani was "making frequent public statements pushing for Ukraine to investigate interference in the 2016 election and issues related to Burisma and the Bidens."

The landmark House impeachment inquiry was sparked after another call, on July 25, in which Trump asked Ukraine President Volodymyr Zelenskiy for "a favour," the investigations.

A still-anonymous whistleblower's official government complaint about that call led the House to launch the current probe.

Hill was an aide to former national security adviser John Bolton and stressed that she is "nonpartisan" and has worked under Republican and Democratic presidents.

She appealed to the GOP to stop peddling an alternative theory of the 2016 election. She contended that Russia wanted to delegitimise "our entire presidency," whether the winner be Trump or Hillary Clinton, by sowing the "seed of doubt" in the outcome.

"This is exactly what the Russian government was hoping for," she said about the currently divisive American political climate.

"They would pit one side of our electorate against the others."

She warned that Russia is gearing up to intervene again in the 2020 US election.

"We are running out of time to stop them," she testified.

"I would ask that you please not promote politically driven falsehoods that so clearly advance Russian interests," Hill said in prepared opening remarks to the House Intelligence Committee.

Trump as well as Republicans on the panel, including ranking GOP Rep. Devin Nunes of California, continue to advance the idea that Russian interference was a "hoax," and that it was Ukraine that was trying to swing the election, part of a desperate effort by Democrats to stop Trump's presidency.

"That is the Democrats' pitiful legacy," Nunes said in his opening remarks.

He called it all part of the same effort, from "the Russia hoax" to the "shoddy sequel of the impeachment inquiry.

Trump has told others testifying in the inquiry that Ukraine tried to “take me down" in the 2016 election and.

But she said the conclusion by US intelligence agencies that Russia meddled in the U.S. election "is beyond dispute."

She said, "I refuse to be part of an effort to legitimise an alternative narrative that the Ukrainian government is a US adversary, and that Ukraine — not Russia — attacked us in 2016," she said. (AP)

(This is an unedited and auto-generated story from Syndicated News feed, LatestLY Staff may not have modified or edited the content body)