Republicans have been clamoring for House Intelligence Chairman Adam Schiff, a California Democrat, to release the Volker transcript, arguing that it contains exculpatory information showing there was no "quid pro quo" between Trump and Ukraine.
In his updated testimony, Mr. Sondland recounted how he had discussed the linkage with Andriy Yermak, a top adviser to President Volodymyr Zelensky of Ukraine, on the sidelines of a September 1 meeting between Vice President Mike Pence and Mr. Zelensky in Warsaw.
Sondland had initially testified that he knew of only one quid pro quo: a coveted White House invitation for Ukraine's new president if Ukraine would commit to launching investigations that could have impugned the reputation of Joe Biden.
Ueland said Trump wants "the spending process to continue to unfold and the government to continue to be funded".
Democrats have called for several witnesses to meet the impeachment investigators this week, including Energy Secretary Rick Perry and former national security adviser John Bolton. "We now know that the call was just one piece of a larger operation to redirect our foreign policy to benefit Donald Trump's personal and political interests, not the national interest".
"'Look back to what happened in 2016, ' certainly was part of the thing that he was anxious about in corruption with the nation", Mulvaney said.
If the House votes to approve articles of impeachment, the Republican-controlled Senate would then hold a trial on whether to remove the president from office.
Some Democrats say Trump, who has ordered administration officials not to cooperate with the impeachment inquiry, should face an obstruction of Congress charge among the counts they plan to consider.
House Democrat impeachment investigators are trying to determine if Trump abused his power by allegedly pressuring Zelensky to investigate Joe Biden and his son, Hunter, and claims of tampering in the 2016 elections during the July 25 call.
Sondland, a major Trump donor, testified on October 17.
House Democrats are seeking a deposition of acting chief of staff Mick Mulvaney on Friday, targeting the highest-ranking White House official to date in the Democratic-led inquiry.He is not expected to comply with the request.
Gordon Sondland says he now remembers telling a Ukrainian official that USA military aid "likely" hinged on a political inquiry sought by Mr Trump.
Democratic U.S. Representative Jamie Raskin, who sits on the Oversight Committee, said the failure of the witnesses to appear would not affect the pace of the inquiry. Trump says he did nothing wrong.
Public hearings could begin as soon as next week in the impeachment inquiry that Trump says is illegitimate and Republicans in Congress call a sham.
Trump has been the target of the inquiry since a whistleblower complaint alleged that multiple White House officials were concerned that the president illegally sought help in an election from a foreign leader and jeopardized national security.
William Taylor, the acting United States ambassador to Ukraine, had repeatedly questioned Mr Sondland in text messages about a quid pro quo, a Latin phrase meaning an exchange of favours.
Most of those who have testified before the House panel are from the ranks of the State Department, including recalled U.S. Ambassador to Ukraine Marie Yovanovitch, whose testimony was released Monday.
Which was ... concerning, shall we say, but not as concerning as Bill Taylor and Alex Vindman and Tim Morrison testifying that they believed military aid was part of the deal too.