Transcript for President Trump defends $130K reimbursement for Stormy Daniels payment
Reporter: Today, for the first time, president trump acknowledging he reimbursed his personal lawyer, Michael Cohen, for the $130,000 payoff to adult film star stormy Daniels. Nice to be back, Sean. Reporter: The revelations first came to light last night when the president's attorney, Rudy Giuliani, dropped the bombshell on Fox News. I'm giving you a fact now that you don't know. It's not campaign money. No campaign finance violation. So they funneled it through a law firm? Funneled through a law firm and the president repaid it. Reporter: This afternoon the white house on the defensive. As mayor Giuliani stated, this was information that the president didn't know at the time, but eventually learned. How could he not have known he was paying him back? Again, I'm not going to get into those details, I would refer you back to the statements, pretty lengthy statements made by Giuliani, both last night and this morning, as well as the president's tweets, where they've both spoken about that. Last night, Rudy Giuliani, for no good reason, seemed to offer up evidence that Donald Trump may have committed a crime in violation of federal campaign finance laws. It was an astounding revelation by trump's own lawyer. Reporter: Giuliani's statements, an apparent contradiction to the president's claims just last month. Did you know about the $130,000 payment to stormy Daniels? No, no. Then why did Michael Cohen ke it if there was no -- You'll have to ask Michael Cohen. Michael's my attorney. And you'll have to ask Michael. Do you know where he got the money to make that payment? No, I don't know. Reporter: In a previous statement to ABC news, Cohen said he facilitated the payment using a home equity line of credit. And that neither the trump organization nor the trump campaign were ever involved. But according to Giuliani, who was also part of the campaign, the payoff was well known. Everybody was nervous about this from the very beginning. I wasn't. I knew how much money Donald Trump put into that campaign. I said, $130,000? You could do a couple of check forth $130,000. When I heard Cohen's retainer of $35,000 when he was doing no work for the president, I said, that's how he's repaying -- how he's repaying it. With a little profit and a little margin for paying taxes. From Michael. Guess what, that's fraud. That's illegal. Reporter: Stormy Daniels' attorney on CNN last night seizing on the moment. I don't care where you line up. You should be disgusted by what has happened in connection with the lies that you have been told over the last three months about this payment. There was no knowledge of any payments from the president, and he's denied all of these allegations. Reporter: In a series of tweets this morning, the president admitting that he did reimburse Cohen through a monthly retainer, adding that money from the campaign or campaign contributions played no role in this transaction. But those initial denials about the hush money the latest in a long list of statements by the president that have turned out to be untrue. Will the president and the white house show what appears to be a blatant disregard for the truth, how are the American people to trust or believe what is said here, what is said by the president? We give the very best information that we have at the time. I do that every single day and will continue to do that every day I'm in this position. Reporter: Sanders said when the president issued his denial on air force one, he did not yet have all the facts. Mayor Giuliani stated this wasn't something that was initially known. But later learned. We still don't know for certain what Donald Trump knew about this payment to stormy Daniels and when he knew it. Reporter: The justice department and the federal election commission had already been looking into how the payment was handled. Campaign finance laws were only violated here if the payment to stormy Daniels was for the purpose of influencing an election. My view is that all the facts strongly point to this being a payment to influence the election. This payment happened right before the general election. At the moment that stormy Daniels was talking to other national major media outlets. Reporter: But this morning on "Fox and friends," Giuliani was adamant no major crimes were committed, insisting the payment had nothing to do with the campaign. It wasn't for the campaign, it was to save their marriage, their reputations. If the jury were to decide this payment is purely for personal reasons, then there was no campaign finance law violation. Reporter: But in that same interview Giuliani seemed to suggest the hush agreement was about the campaign after all. Imagine if that came out on October 15th, 2016, in the middle of the last debate with Hillary Clinton. Right, to make it go away, they made this -- Cohen didn't even ask. Cohen made it go away. Donald Trump could have done all of this without breaking any campaign finance laws. His committee would have had to report the expenditure, the payment to stormy Daniels. But they didn't do that. And as is so often the case, here the cover-up is worse than the payment itself. It's the cover-up that gives rise to all these legal problems. Reporter: This coming two weeks after Giuliani joined president trump's legal team. During the campaign, he was the president's rottweiler. I am sick and tired of the defamation of Donald Trump! Reporter: In the final months before the election, Giuliani was praising trump for his ability to find loopholes in the tax code. He's a genius. It's a perfectly legal application of the tax code. And he would have been a fool not to take advantage of it. How about a little hug? Reporter: Then when that "Access Hollywood" tape was released -- Grab them by the . Do anything. Reporter: Giuliani once again ran to his defense on CNN. The fact is that men at times talk like that. Reporter: Then on Fox News, two days before former FBI director James Comey reopened the Clinton e-mail investigation, Giuliani seemed to foreshadow something ominous. Got a surprise or two that you're going to hear in the next two days. Reporter: That investigation ultimately damaging to the Clinton campaign. On the day that Comey reopened the investigation, Giuliani went on the Lars Larson radio show saying there was a revolution inside the FBI about Comey's original decision to not charge Clinton. He said his sources included former FBI agents and current ones. I know that even from a few active agents who obviously don't want to identify themselves -- Reporter: If current agents had told Giuliani anything about the investigation, this would have been a violation of federal law. The very next day, Giuliani walking it back, claiming he was only talking about former agents. Rudy Giuliani has purported to know what's going on inside the FBI. I don't know how seriously that's being pursued by Bob Mueller but it is intriguing he's dropped those hints in the past. Reporter: Comey would later tell our George Stephanopoulos that the FBI had been investigating whether Giuliani had advance notice from the inside. You had your former boss, Rudy Giuliani, out there on television saying something big was coming. Yes, I saw that. And I don't know whether that was part of what I ordered investigated. Reporter: Some are now wondering if last night's admission that president trump had repaid Cohen came as a result of what had been seized in the FBI raid on Michael Cohen. This appears to be an effort by the trump legal team to get ahead of any revelations that might come out. Reporter: Meanwhile, on the world stage, president trump is moving closer to a summit with North Korea. And at the same time negotiating a release of American hostages. In such a dramatic way, he is shaking up not just the united States, but the global community. A lot of people, that's frightening. What he does on trade, what he does on the Iran nuclear agreement, on the Paris climate accord, on all kinds of alliances and arrangements around the world, he's a disrupter. There are so many different things that should be occupying the time of the white house, and there's been a stark admission from people inside the white house this is having an effect, it is having a drag, it is affecting the presidents' day day-life as he tries to do the business of running the country and participating in world affairs. Reporter: For "Nightline," I'm Tom llamas in New York.
This transcript has been automatically generated and may not be 100% accurate.