The US envoy previously denied any politically motivated aid freeze.
"The investigation has revealed that you may have been directly involved in an effort orchestrated by President Trump, his personal agent, Rudolph Giuliani and others to withhold. almost $400 million in security assistance in order to pressure (Ukraine) to pursue investigations that would benefit President Trump's personal political interests", the chairmen of the three committees leading the probe wrote.
Transcripts were also released Monday as Democrats move toward the public phase of their impeachment inquiry, with public hearings conducted by the House Intelligence and Judiciary Committees likely in the coming weeks.
He had earlier testified that Mr. Trump was clear that there was no quid pro quo for releasing US military assistance.
When Conway gave an interview to Fox & Friends on Wednesday, Steve Doocy highlighted the moment where Sondland said he told a high-ranking Ukrainian official that they were unlikely to receive military aid from the USA until they publicly announce an investigation of Joe Biden's family.
In a three-page update of his original 10-hour testimony, Sondland admitted that he had told one of Ukrainian President Volodymyr Zelensky's advisers that continuing to receive the US aid was tied to their public announcement of two investigations sought by Trump: a probe into a company with ties to former Vice President Joe Biden's son, and another into alleged Ukrainian collusion in the 2016 election.More news: Stabbing at Jordan tourist spot wounds three Mexicans, one Swiss
Sondland testified that he did not ultimately know why the aid to Ukraine was withheld. And with that, a key witness - Trump's best defense witness, until now - apparently concerned about possible perjury charges after a wealth of conflicting testimony from other career diplomats, blew away any previous denials of a clear quid pro quo.
US President Donald Trump and Ukrainian President Volodymyr Zelensky speak during a meeting in NY on September 25, 2019, on the sidelines of the United Nations General Assembly. Mr Taylor had asked. They were questioned last month about President Donald Trump pressuring Ukraine to dig up dirt on his political rivals.
Sondland claimed that he stopped by Hill's office a few days before she was set to leave the White House and that she was "pretty upset about her role in the administration, about her superiors, about the President". "There is going to be political influence in foreign policy", Mulvaney said at the time, although he later contradicted himself.
Volker and Sondland both testified they were disappointed after briefing Trump at the White House upon their return from Zelensky's inauguration in May as a new leader of the young democracy vowing to fight corruption.
The release comes as two White House officials - Wells Griffith, senior director for global energy and environment at the National Security Council, and Michael Duffey, Office of Management and Budget associate director for national security programs - failed to appear for scheduled depositions Tuesday.
Acting White House Chief of Staff Mick Mulvaney's October 17 press conference performance encouraged House Democrats to demand he give testimony before the impeachment inquiry.
On Tuesday, Republicans said they were considering installing Rep. Jim Jordan, R-Ohio, a boisterous Trump supporter, on the House Intelligence Committee as it prepares to hold public hearings.More news: Microsoft freakin' stored the 1978 Superman movie on a piece of glass
The statement never went out after the Ukrainians didn't want to add the references.
William Taylor, the top US diplomat in Ukraine, and Deputy Assistant Secretary of State George Kent will testify on Nov 13, while former US Ambassador to Ukraine Marie Yovanovitch will appear on Nov 15, Representative Adam Schiff, the committee's chairman, said in a statement.
"In the past few weeks, and despite the White House's continued obstruction, we have learned a great deal about what occurred from those with firsthand knowledge of the call, and those who witnessed the president's actions preceding and following it", Schiff wrote in the op-ed. It is uncertain if Mulvaney will appear.
Republicans have been unable to deliver a unified argument against the impeachment probe, but Senate Majority Leader Mitch McConnell said on November 5 he's "pretty sure" how it all will end.
"I can not stress just how wrong this is", Schumer said.
A top Trump ally, Sen.
"I've written the whole process off", Graham told reporters on Tuesday, "I think this is a bunch of B.S".More news: World markets buoyed by growing trade optimism
Sondland closed his addendum to the House investigators saying he may have had a second call with Trump, but has been unable to obtain phone records and "cannot specifically recall" if that was the case.