WATCH: AG nominee vowing to protect Robert Muller's investigation

WATCH: AG nominee vowing to protect Robert Muller's investigation

Transcript for AG nominee vowing to protect Robert Muller’s investigation

And we begin tonight with president’s pick for attorney general and answering questions in front of the American people. William Barr was asked, is the Mueller investigation a witch hunt? He said no. Asked if he would fire Mueller if the president asked him to? Tonight, how he responds to that. And this evening, this question. Will the American people get to see the Mueller report for themselves when he’s finished? What Barr said today, it made immediate headlines. ABC’s chief justice correspondent Pierre Thomas leading us off. Reporter: Tonight, the president’s own pick for attorney general saying he knows Bob Mueller. That he’s a marine, he’s a friend, and that Mueller would not conduct a witch hunt. Vowing to protect the special counsel’s investigation. It is vitally important that the special counsel be allowed to complete his investigation. I have known Bob Mueller for 30 years. On my watch, Bob will be allowed to finish his work. Reporter: Barr defending Mueller against those words the president has tweeted so often. The claim that Mueller is on a witch hunt. Do you believe Mr. Mueller would be involved in a witch hunt against anybody? I don’t believe Mr. Mueller would be involved in a witch hunt. Reporter: And William Barr insisted he would resist any pressure from president trump. I will not be bullied into doing anything I think is wrong by anybody, whether it be editorial boards or congress or the president. Reporter: Democrats pressing Barr, asking him, “Would you fire Mueller if the president asked you to?” Assuming there was no good cause? Assuming no good cause. I would not carry out that instruction. Reporter: And will the American people ever see Mueller’s report? Barr saying today that under justice department guidelines, Mueller’s findings would be confidential, but that in the interest of transparency, he would then release his own summary of the report to the public and congress. He did, however, say that neither trump nor his lawyers would get to edit Mueller’s report. He could take this investigative report, put his own spin on it, correct it before its release. Do you commit that will not happen if you’re attorney general? That will not happen. Reporter: But it was Barr himself who wrote the justice department a memo just last year, raising questions about Mueller’s investigation into possible obstruction of justice. When pressed today about what he wrote — I think it was entirely proper. Reporter: And given what he wrote, when asked what he would do if career ethics officials recommended he recuse himself, Barr said there are different kinds of rescuals. Some mandated, others judgement calls. Let’s imagine it’s a judgment call and the judgment by the career ethics officials in the agency, are that you recuse yourself. Under what scenario would you not follow their recommendation? If I disagreed with it. And what would the basis of that disagreement be? I came to a different judgment. On what basis? The facts. Such as? Such as whatever facts are relevant to the recusal. All right, let’s get to Pierre Thomas, live up on the hill. I want to get what William br said today about that central question. Will the American people, really folks on all sides of this, will they get the chance to read Robert Mueller’s final report for themselves. Reporter: David, they may never see the original Mueller report. That’s going to be submitted to Barr, if he’s confirmed. Barr will write his own summary of the findings and he will decide if it’s released to the public. But Boston line, Barr will decide what we all get to see. David?

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

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