Transcript for Tomorrow’s impeachment showdown
And we are just hours away now from the televised impeachment hearings here in as you likely know, this is only the fourth time impeachment proceedings have played out against an American president. Tomorrow morning, millions will be watching and among the key questions, was there a quid pro did president trump withhold hundreds of millions in U.S. Aid to pressure the new president of Ukraine to investigate the Bidens? Tonight, the first two witnesses who will testify tomorrow, and why they were chosen. And how some Republicans plan to defend the president, holding mock hearings today to prepare. ABC's Mary Bruce up on the hill tonight. Reporter: Less than 24 hours until the first public hearings, Democrats eager to let their witnesses speak for themselves. Madam speaker, what do you hope to begin from the impeachment public hearings tomorrow? We're just having a press conference on dreamers today. Reporter: They've chosen the first two carefully. Bill Taylor, the top U.S. Diplomat in Ukraine, a Vietnam veteran hand-picked by the president's own secretary of state. And George Kent, a senior state department official who has served presidents of both parties. Democrats believe Taylor and Kent will reveal the scope of the effort to pressure Ukraine to investigate the president's political rivals. And outline the stakes for national security. Taylor has testified it was his "Clear understanding" that Ukraine would not receive nearly $400 million in military aid until they agree to investigate the Bidens. An arrangement he described as "Crazy." Kent called american/ukraine policy a "Snake pit," led by the president's personal lawyer, Rudy Giuliani, who hmm accused of running a "Campaign of slander" and "Lies." Republicans plan to cast the witnesses as "Unelected and anonymous bureaucrats." Neither of these two individuals were on the call. Piece folks never talked to the president of the United States about this call. Reporter: Republicans intend to focus narrowly on the president's July phone call, saying there was no pressure when trump asked the Ukrainian president to "Do us a favor" and urged him to investigate the Bidens. But witnesses have testified that call is just part of the story. That Ukraine was explicitly told they would not receive the military aid until they announced that investigation. All right, so, let's get right to Mary Bruce, she's live up on the hill tonight. And we know the televised hearings get under way 10:00 A.M. Tomorrow, and the Democrats and then the Democrats will have long stretches of time to question these witnesses uninterrupted? Reporter: David, the top Republican and Democrat on this committee will each initially have 45 minutes to question the witnesses, giving each party a big chunk of time to try and lay out their case to the American people. After that, each member gets five minutes for questions. David, we're told the whole hearing could last more than six hours. David? All right, we'll be here for it all. Mary, thank you. See you in the morning. And I'll be joining George and the entire team. Live coverage of the house impeachment hearings tomorrow morning, 10:00 A.M. Eastern, right here live on ABC.
This transcript has been automatically generated and may not be 100% accurate.