The following is a transcript of an interview with Senator Chris Van Hollen that aired Sunday, December 22, 2019, on "Face the Nation."

MARGARET BRENNAN: And we now turn to the other side of the table, literally and figuratively. A Maryland Democratic senator, Chris Van Hollen. Good to have you here.

SENATOR CHRIS VAN HOLLEN: It's good to be with you, MARGARET.

MARGARET BRENNAN: So you just heard Senator Blunt lay out his position. You are one of the first senators to publicly float at least this idea that the speaker hold on to those articles and not immediately transfer them. Can you explain the strategy? What do you- what is this leverage?

SEN. VAN HOLLEN: Sure. Absolutely. And first, just to be clear, the conduct we're talking about from President Trump has no parallel in the conduct of anything that President Obama or President Bush did. And his claim of absolute immunity is unprecedented. No presidents ever claimed that. So Speaker Pelosi is doing exactly the right thing. She is focusing a spotlight on the need to have a fair trial in the United States Senate. And it's especially necessary when you have Mitch McConnell, Senator McConnell, who you quoted earlier, saying publicly that he's not going to be an impartial juror, even though that's what the oath will require, that he's going to work in lockstep with the president, who's the defendant in this case, and that he's already said no to calling fact witnesses that have direct knowledge of what's at stake in this impeachment.

MARGARET BREBNNAN: So, you're trying to divide the Republican caucus over these two weeks?

SEN. VAN HOLLEN: We're trying to engage, first of all, the public in a conversation, because almost every American would agree that to have a fair trial you need to have witnesses. I mean, what's a trial without each side being able to call their witnesses? And, yes, they're going to be a number of Republican senators who are going to have to decide on whether or not to call these witnesses. And after all, as you indicated, President Trump says he wants witnesses. Now, I don't know if he's trash-talking or not, but let's have some witnesses. If it was such a perfect phone call, then send on Mick Mulvaney down to talk about that perfect phone call. Send down John Bolton. What are they afraid of?

MARGARET BRENNAN: Do you think Democrats will get on board with what Senator Blunt laid out, which is that the, quote unquote, Clinton model of having debate, then voting on witnesses?

SEN. VAN HOLLEN: I think Democrats want assurances upfront that this is going to be a fair trial and that you're going to be able to call witnesses. There were witnesses called in all the prior trials, most recently the- the Clinton impeachment, and--

MARGARET BRENNAN: And is Speaker Pelosi in lockstep with Schumer on that one, that the articles won't be transferred until there is a promise of witnesses?

SEN. VAN HOLLEN: Look, I think we have to take this day by day.

MARGARET BRENNAN: Okay.

SEN. VAN HOLLEN: I think what Speaker Pelosi is doing is focusing attention on the need for a fair trial, and a fair trial means you get to call your witnesses. Every American knows that, that's what a trial is all about. How can it be a fair trial if you can't put on the rest of your case? There's over- already over--

MARGARET BRENNAN: So, you haven't decided how you will vote--

SEN. VAN HOLLEN: There's overwhelming--

MARGARET BRENNAN: --as a juror yourself?

SEN. VAN HOLLEN: I will wait to hear all the evidence.

MARGARET BRENNAN: Okay.

SEN. VAN HOLLEN: I think that the House has made a very strong case for impeachment, but I will reserve final judgment until all the evidence is- is in. The president says he wants to put forward his case. I don't know why, you know, others aren't saying, "Okay, Mr. President, send down your witnesses." That's what we want.

MARGARET BRENNAN: So, for people at home, though, they- they see and hear the math on this, that it takes 67 votes to actually remove- eject the president from office. And it is incredibly unlikely that those votes will exist, right, at this point, looking at the math as it stands. So given all that, what is the purpose of the standoff over how the trial is conducted, if you know the outcome?

SEN. VAN HOLLEN: Well, the reason that Republicans are so deathly afraid of sending down these fact witnesses is because after they testify under oath- they'll have to raise their right hand, just like all the witnesses in the House did, and testify under penalty of perjury- it's going to be much harder for Republicans to hide behind this myth that this was a perfect phone call. And it will make it harder for those senators to vote for a quit- acquittal. And that is why they're so afraid of having witnesses called. I mean, why else? Why- why wouldn't you send your witnesses down to- to tell the truth under penalty of perjury?

MARGARET BRENNAN: I want to also ask you about something you were working on that was tucked inside a- a bill that the president just signed off on. And this includes giving him more abilities to put different kinds of sanctions on North Korea. We know U.S. intelligence is watching and preparing for the possibility of an upcoming long range missile test by North Korea. Do you believe the president will actually use the sanctions you gave him the authority, or is this-- so, I mean, you have no way to force the hand here?

SEN. VAN HOLLEN: Well, we need to tighten the sanctions regime on North Korea. The United Nations has documented the fact that it's kind of like Swiss cheese. There's a lot of leakage in this. And so this legislation will require the president to put in secondary sanctions. So if you're a company, you're a bank in China, you will now face U.S. sanctions if you keep doing business with North Korea. He's required to do that in 120 days. Now, he can exercise a national security waiver. We have said on a bipartisan basis it would be totally wrong to use those waivers and let North Korea off the hook unless you can show us measurable progress toward reaching our goal of denuclearizing the Korean Peninsula. The time for photo op summits is over. It's time to be serious and let the North Koreans know that we're gonna tighten these sanctions.

MARGARET BRENNAN: And what we know is to date, the diplomacy has not resulted--

SEN. VAN HOLLEN: That's right.

MARGARET BRENNAN: --in any of what you just laid out as a premise for suspending or not enacting these sanctions.

SEN. VAN HOLLEN: That's right.

MARGARET BRENNAN: You think basically it is inevitable that these new sanctions are going on North Korea in the next few weeks?

SEN. VAN HOLLEN: Yes, I do. I think within 120 days, these will be imposed on North Korea and we're--

MARGARET BRENNAN: Because the question is, if they carry out long range missile tests, we don't know what the Trump administration will do other than go to the United Nations. Do you think that this time clock on diplomacy is ticking?

SEN. VAN HOLLEN: Look, the clock is clearly ticking right now. It's been ticking for some time now. You have North Korea now engaged in their saber rattling once again, as- as has been the case from the beginning, we need to engage China. During this period where we've had these summits with North Korea, the president has essentially allowed China to go ahead and allow trade to go back and forth between China and North Korea and- and Chinese banks. So this will put an end to that. It will tighten the sanctions. And I think that's necessary in order to really get a serious negotiation at the negotiating table. If I could just--

MARGARET BRENNAN: Okay.

SEN. VAN HOLLEN: --really briefly say,--

MARGARET BRENNAN: We have to--

SEN. VAN HOLLEN: --with respect to the- the trial--

MARGARET BRENNAN: We have to leave it there.

SEN. VAN HOLLEN: If it's not fair, there's going to be no way that Trump's--

MARGARET BRENNAN: Well--

SEN. VAN HOLLEN: --going to be able to go around and say he's exonerated.

MARGARET BRENNAN: And we'll have plenty of debate over what fair means in the rest of the show--

SEN. VAN HOLLEN: Absolutely.

MARGARET BRENNAN: Thanks to both of you, senators.

SEN. VAN HOLLEN: Thank you.

MARGARET BRENNAN: We'll be back in one minute with another Democrat, Senator Amy Klobuchar from Iowa.