Transcript for 'Going to insist ... underlying evidence' in Mueller report made public: Rep. Schiff

Michael Cohen we'll take the Washington spotlight. Three days of hearings on Capitol Hill including blockbuster public testimony and else on Wednesday. Cohen's lawyer says he's prepared to reveal damning details of his years as Trump's attorney in fixer promising a chilling portrait of the president. It comes Cohn continues to cooperate prosecutors offering leads and the possible corruption of the trump inaugural and insurance irregularities at trumpet organization. And that investigation in New York southern district just one of several probes poised to challenge the president well beyond the end of Robert Muller's work. We start with a man leaning one of those investigations the chair of the House Intelligence Committee Adam Schiff congressman Schiff thank you for joining us. This yearning Michael Collins can appear before your committee behind closed doors on Thursday what do you hope to learn from him that you don't already know. Well a great deal starting with though why the false statements and before committee when he first appeared. Did they go beyond what he told us about Moscow trump tower. Into other areas as well who would have been aware of the false testimony that it was giving. What other a light can he shed now that he's cooperating on issues of obstruction of justice or collusion. What more can you tell us about the trump tower New York meeting or any other issues relevant to our investigation. We think he has a lot to offer hello. On the finances of the Trump Organization you've suggested that's the new front. In your committees in the investigation. Oh this is something Georgia's you know I've been concerned about for two years now we weren't really permitted to explore it in great detail. When the Republicans are running the committee. But we know already and Michael Cohen is pivotal to this. The apparel of ignoring or observing this red line of the presence and ignoring the financial issues. What we have learned to date. About Moscow trump tower is chilling and that is as Donald Trump was campaigning for president. Even when he became the presumptive nominee of the Republican Party and was telling the country had no business dealings with a Russia. He was privately through his organization seeking the Kremlin's help to make what may have been the most lucrative deal this life. Even reportedly offering an inducement imprudent to make it happen. At the same time talking about removing sanctions on Russia is something very important the Russians. That is deeply compromising. Whether it's criminal or not it is deeply compromising our national security so those issues have to be probed and they include money owed. Well I guess a question about the Mueller investigation if it turns out as the president said so many times that he did not collude with the Russians to interfere. Any election but in fact he was pursuing this trump tower at the same time if that's not criminal to smaller ever have a responsibly reported are not. He does have a responsibility to report it and in fact. If you take a position and I think it's a flawed one but he particular position that the president cannot be indicted. And the only remedy for improper illegal or other conduct is impeachment. Then you cannot withhold that information from congress or were essentially the president has immunity. So that cannot be allowed to be the case Bob Bauer or bill Barr has committed in this testimony. To making as much of the report public as he can and the regulations allow him to make it all public and we're gonna insist on it becoming public. And more than that George we're gonna insist on. The underlying evidence because there is certain. Evidence that is only in the hands of the Department of Justice that we can't get any other way there was searches conducted for example of Roger Stone and Paul Matta Ford. There's no other way to get the information that was seized except to the department. And we can't tell his country fully what happened. As you know William Barr may have quite a different view what those regulations require they knew they could allow him. To release the entire report but under just fire regulations. Officials have said that. If you declined to prosecute someone then the underlying evidence should not be released. But George State Department has so violated. That policy. Repeatedly an extended let it be an intuitive to a great extent. Over the last two years in fact I've had this conversation with Robert Rosen Stein and others on down of the Justice Department. As they turned over thousands and thousands of pages of discovery in the Clinton email investigation. And there was no indictment in that investigation. That this was a new press that they were setting and they were gonna have to live by this president. Whether it was a congress controlled by the Democrats or Republicans so they're going to have to abide by that and I think also quite separate apart from president already set is the intense. Public need to know here which I think overrides any other consideration you. See you say you say that just firms got to live by that precedent that would if they don't what if they simply say no. We're rock and releasing underlying evidence what options you have. Well we will obviously subpoena the report we will bring Bob Mueller in to testify before congress we will take to court if necessary. And in the end I think the department understands. They're gonna have to make this public I think bar will ultimately understand that as well bark comes into this job a two strikes against him. He applied for the job by demonstrating a bias against them on investigation indeed that's. Part of the reason he was hired he's also not been willing to commit to fall on the advice of ethics lawyers indeed that was part of the reason he was hired. If he were to try to withhold try to bury any part of this report. That will be his legacy and it will be a tarnished legacy so I think they'll be immense. Pressure not only on the department but on the attorney general to be forthcoming in talking about public pressure prepared take the administration to court. Absolutely. We are going to get to the Bob of this. A we are gonna share this information with the public and if the president is serious about all of his claims of exonerate shouldn't. Then he should welcome the publication of this report. The president said no collision many times as I said you said many months ago that you've already developed. Evidence of collusion we haven't seen that from from Robert Mueller do you have any evidence at all that the president colluded. George there's ample evidence of collusion of the campaign and it's very much in the public record. And it's everything from what we have seen recently about Paul man a fort meeting with some of linked to Russian intelligence. And sharing polling data and not top line data or not this is why we think trump is gonna win data. But raw data complicated data now we've seen evidence of Roger Stone in communication. When WikiLeaks we've seen the president's son having a secret meeting a trump tower. That was presented him as part of the Russian government's effort to help the trump campaign. His acceptance of that help his interest in getting that. All of this is evidence of collusion and there's much much more. Whether that will amount to a criminal conspiracy that can be proved beyond a reasonable doubt we'll have to wait for Bob Mueller tell us. But 22 would not see what is plainly in front of us. Means you you basically don't want to see the evidence of collusion because it is quite abundant congressman Schiff thanks for time this morning.

This transcript has been automatically generated and may not be 100% accurate.