Rep. Adam Schiff, the Democrat leading the House impeachment probe, announced Wednesday that the first open hearings will be held next week as Democrats continue with the public phase of their investigation.
The move marks a significant ramping up of the impeachment inquiry.
"Those open hearings will be an opportunity for the American people to evaluate the witnesses for themselves, to make their own determinations about the credibility of the witnesses, but also to learn firsthand about the facts of the president's misconduct," Schiff told reporters.
(MORE: In revised testimony, Sondland contradicts Trump, describes quid pro quo with Ukraine )Schiff said the House Intelligence Committee would hear from the top U.S. diplomat in Ukraine, Ambassador William Taylor on Wednesday Nov. 13, as well as from Deputy Assistant Secretary of State George Kent.
(MORE: Some GOP senators buck President Trump, Rand Paul on calls to release whistleblower's identity )Then, on Friday Nov. 15, the committee is scheduled to hear from former U.S. Ambassador to Ukraine Marie Yovanovitch.
White House deputy press secretary Hogan Gidley, in an interview on Fox News, mocked Schiff's announcement, saying "... every time I look up he's on television spewing more nonsense and telling more lies. it happens time and time again because he's sure not working for the American people. What he's putting forward here is more proof that this is an illegitimate impeachment scam.
"He's not going to allow us to put forth any witnesses. He's not going to allow us any cross examination. So, this furthers the problem that he's doing everything to try and hurt the president and nothing for the American people," he said.
ABC News' Alisa Wiersema, Lauren Lantry and Ben Gittleson contributed to this report.