Congressional Democrats have announced they will launch a major new phase of their impeachment inquiry next week with public hearings.
Until now, evidence over allegations that US President Donald Trump's administration withheld aid to Ukraine to force it to investigate his political rival, Joe Biden, have been held behind closed doors.
The first televised hearings will feature three State Department officials who have testified of their concerns about Mr Trump's dealings with Ukraine.
House intelligence committee chairman Adam Schiff, who is leading the impeachment investigation, announced on Wednesday that the committee would hear from top Ukraine diplomat William Taylor.
Career department official George Kent and former US ambassador to Ukraine Marie Yovanovitch would also testify in hearings next Wednesday and Friday.
All three have already given testimony behind closed doors in the first phase of the investigation.
Ms Yovanovitch, who was sacked in May under Mr Trump's direction, told investigators she had been told to "watch my back" and that people were "looking to hurt" her.
Mr Kent and Mr Taylor testified of their concerns about her removal as the president's lawyer, Rudy Giuliani, took a leading role on Ukraine policy.
Despite Mr Trump's daily denials, Mr Schiff said on Wednesday that the witnesses would show "the most important facts are largely not contested" in the inquiry.
Mr Trump, backed by Mr Giuliani, asked new Ukrainian President Volodymyr Zelenskiy in a July call to investigate Mr Biden and his family, and Ukraine's possible role in the 2016 presidential election.
The impeachment investigators are also releasing transcripts of more of the closed-door interviews this week, including Mr Taylor's evidence on Wednesday.