NOEL KING, HOST:
The Senate has opened President Trump's impeachment trial. Supreme Court Justice John Roberts presided over the ceremony yesterday. Senators stood at their desks to swear an oath of impartial justice as jurors. Now, that happened just a few hours after a government watchdog said that the president violated federal law by withholding military aid from Ukraine.
And Lev Parnas, the indicted associate of Rudy Giuliani who's become a central figure in the impeachment case, is continuing to talk about his version of who knew what and when. Last night, he went on CNN and he said he had this message for the Senate.
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LEV PARNAS: I should be their No. 1 witness because I'm the one that got all the dirt, supposedly. Why aren't they calling me to testify? Why do they need Biden? Call me. Ask me what Biden did wrong. I think they're very afraid of me.
KING: Ross Garber has been watching all of this develop. He's an adjunct professor at Tulane Law School, where he teaches political investigations and impeachment. And he has also represented four state governors in their impeachment proceedings. He joins us on Skype. Good morning, sir.
ROSS GARBER: Good morning.
KING: All right. So you heard Lev Parnas there offering himself up as a witness. He alleges the president was directly aware of the campaign in Ukraine to pressure the government to investigate the Bidens. Now, there are questions about Lev Parnas's credibility, for sure. Do you think his claims will be significant to this trial?
GARBER: Well, I think his claims are potentially significant to the issues. You know, I've listened to the interviews with Lev Parnas, and he offers a lot of, you know, potentially valuable and relevant information, and he has provided a lot of documents to the House of Representatives. Now, the question is, will there be enough time to vet all of that information? Because questions have also been raised about his credibility and the detail of his knowledge. So I have my strong doubts - very strong doubts - about whether he will actually be called to testify at the Senate trial.
KING: OK. We still don't know whether more witnesses will be called to testify, leaving Lev Parnas out for a second. Would Republicans risk anything by not calling on witnesses and by not admitting new evidence?
GARBER: Well, so that is the question, and I think there are several potentially swing Republicans, in states with both Republicans and Democrats, who may be feeling some pressure from some of their constituents to allow witnesses. There are also some Republican senators in very heavily Republican states that may feel the call of conscience to call witnesses.
But we have to remember that in the House, zero Republicans voted in favor of even starting the impeachment inquiry. Zero Republicans voted in favor of the actual impeachment. And the president has been pretty tough on Republicans who don't support them. So I think Republicans - some Republicans - may feel some pressure to allow witnesses, but there's also going to be a very, very strong countervailing pressure to not call witnesses.
KING: There is also the question, right, though, with all of this new evidence emerging seemingly at the last minute - there is a question of whether the senators, who are acting as jurors, are working with all of the relevant information, right?
GARBER: Yeah, indeed. I mean, and, you know, part of that is that this investigation - and I don't fault the lawyers who conducted the investigation, because they were given very, very limited time - this was a complicated investigation, it was conducted very quickly. And it is no surprise that there is lots of potentially valuable information that just hasn't surfaced yet. And it's one of the difficulties of doing it so fast and getting it to the Senate so quickly. But one of the things that we're hearing, and I think we're going to continue to hear, is that the Senate, and particularly Senate Republicans, are going to say, that is not the time and place. Trial is not the time to start vetting completely new information.
KING: OK. One of the things that has surfaced in the past day is this decision from the federal watchdog, the Government Accountability Office. This is a nonpartisan group. They ruled that the White House illegally withheld aid to Ukraine, that that move was illegal. Will that be significant during this impeachment trial?
GARBER: I think it's potentially significant as a matter of oversight, that the White House potentially and the president potentially acted unlawfully. But in terms of the impeachment trial, I think it's not going to be significant...
KING: Why not?
GARBER: ...Because, remember, the ultimate question is whether to remove the president. And this opinion is, I think, going to be portrayed by Republicans as just that - it's an opinion. What we haven't seen is a testimony or information that anybody told the president that he was acting illegally and acting unlawfully.
In fact, quite to the contrary, this decision seemed to have been vetted by White House lawyers who seemed to assure the president and his aides that this was OK. And so you don't remove a president for doing something that was unlawful unless it rises to that level of treason, bribery, high crimes and misdemeanors, which I think would take, at a minimum, knowledge that he was acting unlawfully.
KING: OK. So the same thing, essentially, that we've been litigating all along. As you watched those senators swear the oath yesterday, you think back to past impeachments this country has seen, what makes this trial unique?
GARBER: Yeah. So this trial is unique for several reasons. I mean, the first is it's the first impeachment trial of a president who's actually running for reelection. And that's significant - the voters are going to have the chance to make a decision in just a few months. And second is that this was handled, you know, quite quickly, and so there is a lot of information that is going to potentially arise...
KING: That we just don't know yet. Yeah. Ross Garber of Tulane, thank you so much for taking the time.
GARBER: You bet. Transcript provided by NPR, Copyright NPR.