Transcript for High-stakes televised impeachment hearings set for next week
Next tonight, the historic showdown on capitol hill. The impeachment inquiry going public, with high-stakes televised hearings set for Wednesday and Friday. First up, William Taylor, who already testified it was clear millions of military aid would be withheld unless there was an investigation into the president's political rivals. Taylor called this, quote, "Crazy." Republicans have their own list of people they want to hear from, including hunter Biden and that anonymous whistle-blower. David Wright is at trump tower Reporter: Tonight, with the impeachment inquiry about to enter a new public phase, the battle lines are drawn over who should testify. They're having people, I never even heard of some of these people. I don't know who they are. And, by the way, it's all third-hand knowledge. Reporter: That's not true. The committee has heard from several witnesses who were on that July phone call in which president trump asked Ukraine to investigate the Bidens. As it stands, the first witness scheduled to appear is America's top diplomat in Ukraine, William Taylor. Behind closed doors, Taylor has already testified it was his "Clear understanding" there was a quid pro quo. $400 million in U.S. Military aid contingent on Ukraine announcing a corruption investigation of president trump's political rivals. An arrangement Taylor called "Crazy." This is a very strong case of bribery. Reporter: Republicans, for their part, want to hear from hunter Biden. And the anonymous whistle-blower, who first sounded the alarm that resulted in the impeachment inquiry. If they don't call the whistleblower in the house, this thing is dead on arrival on the senate. Reporter: But the chair of the house intelligence committee said calling the whistle-blower would only place their personal safety at risk. Adam Schiff also appeared to reject calling hunter Biden, warning that the impeachment inquiry should not be a vehicle "To carry out the same sham investigations that president trump pressed Ukraine to conduct for his personal political benefit." We want to stay focused on the Ukraine call. And having hunter Biden come in is unrelated to the Ukraine call. David Wright joining us from outside trump tower in New York. Where the president is preparing to appear at tomorrow's veterans day parade. A large security presence there behind you. And the president is getting some support tonight from his former U.N. Ambassador? Reporter: That's right. Nikki Haley has a new book coming out. Saying how former secretary of state Rex tillerson and former chief of staff John Kelly approached her and asked her to save the country by undermining president trump. She says she said no. Tom? David, thank you. And there will be complete ABC news coverage of the house impeachment hearings starting Wednesday at 10:00 A.M. Eastern. Right here on ABC and on ABC news live.
This transcript has been automatically generated and may not be 100% accurate.