ASHINGTON, Oct. 22 -- The top U.S. diplomat in Ukraine told congressional lawmakers in a testimony Tuesday that President Donald Trump linked millions of U.S. dollars in military aid to Kiev to a pledge by the Ukrainian president to investigate Trump's political rivals.

Testifying behind closed doors before members of House committees probing the Trump administration's alleged inappropriate interactions with Ukraine, U.S. Charge d'Affaires to Ukraine William Taylor said Trump made 391 million dollars in defense assistance Washington promised to Kiev contingent upon Ukrainian President Volodymyr Zelensky agreeing to investigate U.S. Democratic presidential candidate Joe Biden and Ukraine's alleged involvement in foreign meddling in the 2016 U.S. election.

Taylor said in a prepared opening statement, which was later released by U.S. media, that he was told that Trump "did insist that President Zelensky go to a microphone and say he is opening investigations of Biden and 2016 election interference, and that President Zelensky should want to do this himself."

Trump, however, in a phone call with U.S. Ambassador to the European Union Gordon Sondland on Sept. 7, said he was not asking for a "quid pro quo."

Taylor, who served as U.S. ambassador to Ukraine in former President George Bush's administration between 2006 and 2009, adopted a different spelling of the Ukrainian president's last name in his written testimony.

Sondland, according to the testimony, told Taylor via phone on Sept. 8 that "Trump was adamant that President Zelenskyy, himself, had to 'clear things up and do it in public.'"

Sondland in the phone call also informed Taylor that he had told Zelensky that failing to "clear things up" in public would lead the U.S.-Ukraine relationship to a "stalemate," and that the Ukrainian leader eventually agreed to make a public statement on the matter. Taylor told the lawmakers that he "understood a 'stalemate' to mean that Ukraine would not receive" the military assistance.

White House Press Secretary Stephanie Grisham issued a statement Tuesday night in response to reports about Taylor's testimony, insisting that "President Trump has done nothing wrong."

She called the Democrat-led impeachment inquiry stemming from a controversial Trump-Zelensky phone call on July 25 "a coordinated smear campaign from far-left lawmakers and radical unelected bureaucrats waging war on the Constitution."

"There was no quid pro quo," Grisham added.

Trump has repeatedly defended his July 25 phone call with Zelensky as being "perfect" and accused the impeachment proceedings of lacking "due process." He once again took to Twitter to vent his fury Tuesday morning, calling the inquiry "a lynching" -- an assertion dismissed by his opponents as a racist trope.

The Trump administration notified Congress on Sept. 11 that the aid to Ukraine had been disbursed.

Trump told reporters on the sidelines of the United Nations General Assembly in September that he had withheld the aid from Ukraine because European countries didn't pay their fair share to help Kiev defend its national security.