AMNA NAWAZ: It's the beginning of one of the most anticipated weeks of the presidential campaign so far.

Republican candidates are set to debate in Wisconsin.

But there will be one notable absence.

Former President Donald Trump, leading in the polls, is instead set for processing in a Georgia jail.

Who better to talk about this busy week than our Politics Monday team?

That is Amy Walter of The Cook Political Report With Amy Walter and Tamara Keith of NPR.

Great to see you both.

Thanks for being here.

(CROSSTALK) AMNA NAWAZ: Let's talk about this.

The first debate now just two days away, hosted by FOX.

Here's a look at who has qualified for the debate stage so far, meeting all the threshold, those nine candidates there.

We just mentioned, of course, Mr. Trump will not be there.

We should also mention Francis Suarez and Perry Johnson say they have qualified, but the RNC is deadline to confirm participants, it's 9:00 p.m. Eastern tonight, so that could change.

Amy, Trump won't be there.

But the man running a distant second to him so far in most polls, Ron DeSantis, will be there.

What does a good debate night look like for him?

AMY WALTER, The Cook Political Report: Yes.

Well, first, let me start by saying Trump will be there, but he won't be there.

Trump is going to going to be overshadowing all of this.

And to your point that, even after the debate, we're going to find out, has he turned himself in yet in Fulton County?

What about this interview he's doing with Tucker Carlson?

Will he make some news there that may overshadow what happens in the debate?

So he will have a presence even though he won't be.

And, of course, many of -- he won't be there physically.

And, of course, the candidates will be asked about him.

AMNA NAWAZ: Right.

AMY WALTER: But DeSantis is right.

He's the person that has so much riding on this.

Earlier this year, he could make the case credibly that it was basically a two-person race between he and Donald Trump.

Now a lot of candidates are starting to be nipping at his heels as he has descended.

That's not a place you want to be in polling is going down this way since earlier this spring.

AMNA NAWAZ: Yes.

AMY WALTER: And there is this one opportunity in this debate to sort of settle things down.

Now, can he win this debate?

Perhaps.

And I think, for him, winning would look like not -- one, not slipping any further, not making any mistakes, and, two, that the other potential challengers to his second-place status, Tim Scott and Vivek Ramaswamy, do not overshadow him, because that is really the biggest threat to him right now, is that he's no longer the candidate in second place.

AMNA NAWAZ: But, Tam, as you know, Mr. Trump has had a commanding lead.

We saw that in this latest Iowa poll out today as well.

Those caucuses are still five months away.

But that is a pretty strong lead there, 42 percent for Mr. Trump, in second place there Mr. DeSantis at 19 percent.

As Amy mentioned, he's not going to be at the debate physically.

He's sitting down for an interview with Tucker Carlson, who was formally ousted from FOX.

But what does what does that say to you about who he's trying to reach and who he doesn't care about speaking to?

TAMARA KEITH, National Public Radio: So, he is running like an incumbent president.

And hey, he never admitted that he lost the last race.

He's not running like someone who lost and is scraping his way back.

He's running like the president of the United States who doesn't need to dignify this with his presence.

And an actual incumbent wouldn't attend one of these debates either.

So, he is doing what he does best, which is get absolutely everybody to talk about him.

There will be clips from the Tucker Carlson interview, whether they're played during the debate or after the debate.

He's making it extremely awkward for FOX, which is, of course, a feature, not a bug.

It's all part of what he does.

And I think, for Ron DeSantis, the challenge is, are they all going to focus on him... AMNA NAWAZ: Right.

TAMARA KEITH: ... or everybody else on that stage?

And it's a really big stage?

Or will they focus on Trump?

The problem is that, for most of them, there is no applause line attacking Trump.

There's no applause line at all attacking Trump, because most of the people who are watching that debate are locked in to vote for Trump already.

AMNA NAWAZ: What about President Biden?

Is he going to be watching?

What's the White House saying?

(LAUGHTER) TAMARA KEITH: Well, Principal Deputy Press Secretary Olivia Dalton was asked about it today on Air Force One.

And she said, "I hope he isn't watching for his sake," though she doesn't know whether he will be watching or not.

The Biden campaign and the Democratic Party are planning a lot of rapid response, because, of course, the one other person who can get applause for these folks is attacking Joe Biden or Kamala Harris.

So, he certainly could take a hit in this debate.

And so they're also putting out $25 million in ads over the next several weeks, basically trying to convince voters that the economy is good and that Joe Biden should get credit for it.

AMNA NAWAZ: Amy, the other interesting thing from those Iowa polls was that 40 percent of the caucus-goers said their mind is made up; 52 percent said they're persuadable, right?

What does that say to you?

AMY WALTER: Right.

So, if you are a not-Trump candidate, you say, well, look, there's still majority of people out there who say, they could be open to something.

Now, you and I could be open to a lot of things, and that at the end of the day we don't follow through on, right, like eating certain foods or doing certain things.

We may when we get there say, well, actually, I am not going to follow through on that.

That's the first.

(CROSSTALK) AMNA NAWAZ: ... follow-up questions to what you just said.

(CROSSTALK) AMY WALTER: Yes, I know, we will get to that in a minute.

(LAUGHTER) AMY WALTER: But the more important thing about that 40 -- that 52 percent number of people who say they're open to somebody else, when you look under the hood... AMNA NAWAZ: Yes.

AMY WALTER: ... right now, those voters are not coalescing around another candidate.

AMNA NAWAZ: Right.

AMY WALTER: Donald Trump still gets 27 percent of those voters.

Ron DeSantis gets 25.

And another chunk of those votes go to Tim Scott.

So, fundamentally, the challenge feels very similar -- for non-Trump candidates feels very similar to where we were in 2016.

Even if Trump's base is not as big as these polling numbers suggest, it's more like 35 or 40, that is enough to win if the people who are looking around for somebody else end up splitting their vote between multiple candidates, which is why this is really a race -- this debate is a race for who is in second place.

Who can now lay claim to being the one candidate that everybody else who doesn't want Trump to be the nominee should rally around?

AMNA NAWAZ: Tam, meanwhile, we have got a possible split screen here of the debate and the other candidates and Mr. Trump turning himself in to a Fulton County jail.

He's now facing four separate indictments, 91 charges total.

Is there any sign you have seen that the mounting legal challenges could just cause him to collapse under the weight at some point?

TAMARA KEITH: They're not, I think, a lot of Republican base, base voters who have read those indictments, simply speaking.

They are not interested in it.

They -- the former president and his allies and many of his opponents, in fact, have laid the groundwork for Republican voters to feel as though it's all rigged against Trump, they're all out to get Trump, everything is corrupt.

So why would they care about these indictments?

These indictments just prove that the establishment doesn't want Trump to be president again?

That is the message that Republican base voters have taken from this.

I don't know what could potentially move the needle, except maybe an actual trial and if that trial is televised.

And many of these courts won't allow cameras or even, like, electronic communications from inside the courtroom, and you're dealing with sketches.

So it's -- and we also don't know when any of these trials could actually get set, when these dates will actually happen, because there are going to be numerous appeals and other efforts on the Trump side to slow it all down.

AMY WALTER: And we saw in some other polling, national polling that was out this week by CBS, that even among those voters who Tam rightly points out don't think that he did anything wrong, they still see him as the most electable candidate, the most likely to beat Joe Biden.

So the idea that having all of these indictments is going to weigh him down against Biden, that's not what Republican voters believe right now.

AMNA NAWAZ: And he's only gotten stronger over time, as we have already seen.

AMY WALTER: That's right.

That's right.

AMNA NAWAZ: Amy Walter, Tamara Keith, always good to see you.

Thank you.

AMY WALTER: Thank you.

TAMARA KEITH: Thank you.