Transcript for Will Trump invoke executive privilege and stop Comey from testifying?

before the American people. Tonight, ABC news has learned lea he's prepared to talk about what he wrote in his memos, and whether he felt pressured by the president in the Russia investigation. The white house asked if he's going to block the testimony. Here's Pierre Thomas. Reporter: Tonight, as fired FBI director James Comey prepares to testify before the American people, the white house will not say whether president trump might try to stop him. When asked if the president will invoke executive privilege over his meetings with Comey, the press secretary acknowledges tonight, no decision has been made. And they're not ruling out the idea of blocking Comey. I think, obviously, it's got to be reviewed. So is that -- that's not a no? No, I was just saying, I don't -- it literally -- my understanding is the date for that hearing was just set. I've not spoken to counsel yet. I don't know what they're going to -- how they're going to respond. Reporter: Counselor to the president kellyanne Conway said today it's up to the president. The president will make that decision. Reporter: Comey is expected to testify before the senate intelligence committee, where he will be asked about his private meetings with the president. Whether Comey was asked for a pledge of loyalty from president trump, and whether the president asked him to go easy on Michael Flynn, who lasted 24 days on the job. And congress is expected to ask Comey about what could be the most revealing piece of evidence yet -- those memos Comey privately kept after his meetings with the president. The firing of Comey came after the president once joked with him, you're becoming more famous than me. Weeks later, allegedly calling Comey "A nut job" in the oval office with the Russians. But tonight, some legal scholars say if the president tries to stop Comey from testifying, it could be a tricky move. That invoking executive privilege at this stage could be a challenge. Especially because president trump has already spoken publicly himself about his private meetings with Comey. "Comey better hope there are no tapes about our meetings." And saying this about their private dinner. We had a very nice dinner and at that time he told me you are not under investigation.

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