Transcript for Ambassador Sondland gives bombshell testimony, contenders face off at Dem debate
Reporter: Ever since the impeachment inquiry began. No quid pro quo. No quid pro quo. Reporter: President trump has repeated the same phrase like a mantra. But today on capitol hill. Was there a quid pro quo? The answer is yes. Reporter: A different story from the man the president tapped to work alongside his attorney, Rudy Giuliani. We did not want to work with Mr. Giuliani. Simply put, we were playing the hand we were dealt. Reporter: Overseeing Mr. Trump's policy. For a white house visit for Mr. Zelinsky, Mr. Giuliani demanded Ukraine make a public statement announcing the investigations of the 2016 election DNC server and burisma. Mr. Giuliani was expressing the desires of the president of the United States. What Gordon sondland is for the first time bring the impeachment inquiry directly into the white house with a witness who can testify to what president trump said and did, and it was riveting. Reporter: Ambassador sondland not only admitted there was a quid pro quo. Everyone was in the loop. It was no secret. Reporter: He named names. Many people. Secretary Pompeo? Yes. And acting chief of staff Mulvaney? Yes. Reporter: Sondland said he was concerned military aid and a coveted white house visit were being held up until Ukraine publicly announced an investigation into the Bidens and the 2016 election. He said he reported his concerns about the aid personally to vice president Mike pence. And vice president pence nodded his head? I don't recall any exchange. I think he, it was a duly noted. He didn't say Gordon, what are you talking about? No, he didn't. He didn't say what investigations? He did not. Reporter: That brought swift denials today from the vice president's office, the secretary of state and the white house. Sondland cannot be dismissed as a never Trumper. He's a life-long Republican who donated about a million dollars to president trump's inaugural committee. He is a hard-edged business guy in the hotel business. Very successful. Very smart. But not somebody who's spent his life in diplomacy, and certainly not somebody who spent his life as a witness. I was surprised by kind of how comfortable and nonplussed he appeared while delivering what a lot of people are seeing as bombshell after bombshell. What I would think is kind of surprising is that he didn't sweat more. The suggestion that we were engaged in some irregular or rogue diplomacy is absolutely false. Reporter: Sondland says it was clear to him who was calling the shots. Ambassador Volker and I worked with Mr. Rudy Giuliani on Ukraine matters at the express direction of the president of the United States. I followed the directions of the president. When the president says, talk to my personal lawyer, Mr. Giuliani, we followed his direction. Reporter: But he was fuzzy on some of the details. I don't recall. I don't recall. I don't recall. I honestly, honestly don't remember. Reporter: He blamed it on two things. One personal. I'm not a note taker or memo writer, never have been. Reporter: The other thing he blamed was the trump administration's decision to stone wall the investigation. As a result, sondland said he couldn't refer back to his e-mails, schedule and other items. My lawyers and I have made multiple requests to the state department and the white house for these materials. In the absence of these materials, my memory, admittedly, has not been perfect. Reporter: There was one interaction about which sondland was crystal clear. The phone call he with the president on or about September that's after the white house was already well aware of the whistle-blower complaint. Whether it was the 9th or the 8th, you had this call. It was extremely memorable, right? It was. Reporter: In that call, he was following up on concerns raised by bill Taylor. I said on the phone, I think it's crazy to withhold security assistance for help with a political campaign. Reporter: Sondland testified today that he did reach out to the president. I believe I just asked him an open-ended question, Mr. Chairman, what do you want from I keep hearing all these different ideas and theories and this and that. What do you want? And it was a very short, abrupt conversation. He was not in a good mood. And he just said "I want nothing, I want nothing. I want no quid pro quo." Tell Zelinsky to do the right something to that effect. Reporter: President trump seized on that one sound bite. I just noticed one thing, and I would say that means it's all over. Reporter: Trump scrawled it out with a sharpy to make sure he got it just right. And now, here's my response. That he gave. Just gave. Ready? You have the cameras rolling? I want nothing. That's what I want from Ukraine. That's what I said. I want nothing. I said it twice. That's a big point for the president. Now, it came after the white house knew there was a whistle-blower complaint about that July 25th call with the president of Ukraine. So Donald Trump might have been covering his tracks in that phone call, since he already knew there were people who were blowing the whistle. Reporter: Privately, white house officials acknowledge that sondland's testimony raised problems for the president. He was tense as he watched. From a substantive point of view, the winner today were the Democrats. But they were also the losers today, because the Republicans poked holes in sondland's testimony that may blunt some of the power of his words. Reporter: One significant issue where Republicans raised doubts was whether the $400 million in military aid was part of the quid pro quo. It became your clear understanding that the military assistance was also being withheld, pending salienski announcing these investigations. Correct. That was my presumption. Reporter: Sondland admitted the president never said so explicitly. I don't recall president trump ever talking to me about any security assistance, ever. So is this kind of a two plus two equals four conclusion that you reached? Pretty much. Reporter: Republicans pounced. No one told you president trump was tying aid to investigations. Yes or no? Yes. So you really have no testimony today that ties president trump to a scheme to withhold aid from Ukraine in exchange for these investigations. Other than my own presumption. Which is nothing. Now my colleagues seem to think unless the president says the magic words that I hereby bribe the Ukrainians, that there's no evidence of bribery or other high crimes and misdemeanors. Reporter: Today's impeachment drama easily overshadowed what would otherwise be a big political story. The democratic presidential contenders' debate in Georgia. I have made it very clear this is impeachable conduct. We have a criminal living in the white house. In is not a man who had any qualifications, except one. He wrote a check for a million Reporter: Former vice president Biden. He doesn't want me to be the nominee. We can deal with trump's corruption but we also have to stand up for the working families of this country. Reporter: Some Georgia voters said that's as it should be. My interest is student loan debt, police brutality. As a student, loan forgiveness. Reporter: In Atlanta, where the population is more than 50% African-American, we went to a watch party with voters. Sponsored by two predominantly black voters' rights groups. Some voters do care about those impeachment hearings. Think about it. If you have no respect for the law, that's the constitution, you have no respect for the law period. Reporter: Tomorrow in Washington, one more day of public hearings before the committee begins to move this process along. Have they proved quid pro quo at this point? I think the Democrats have made a very powerful case. But should this be grounds to remove the president from office? That's a separate question. And be sure to tune in to continuing coverage of the impeachment hearings tomorrow morning right here on ABC.
This transcript has been automatically generated and may not be 100% accurate.