Political contributor and former Republican congressman, John Katz-Koh. John, how well do you think the candidates did tonight on covering issues that Republican voters care about?

Now, they certainly talked a lot about the issues. They certainly took a lot of swipes at each other, which I think was indicative of part desperation, a part understanding the moment. It's a very unique opportunity for the two second-place runners to really solidify that second-place spot. It was a lively back and forth, and I think they both landed punches. I think the most important part of the night for Haley, for example, though, was her closing argument where she said, I can win. And she cited irrefutable polling facts to do so. And she also pointed to his campaign spending and how it hasn't helped him. Other than that, I thought it was a really good back and forth. I thought both landed punches. I thought they both could have done better, and they both lived to fight another day. But for DeSantis, he didn't need to land more of a knockout punch here. And going Coming into New Hampshire, he's polling so badly. I think he's really going to struggle.

Chris Christie, of course, ended his presidential bid today in New Hampshire and made a strong statement against the former President. Let's take a listen.

I am going to make sure that in no way do Why enable Donald Trump to ever be President of the United States again. That's more important than my own personal ambition.

As a moderate within the Republican Party who voted to impeach Trump, what do you make of him making this statement when then not throwing his support behind any candidate to help defeat Trump in New Hampshire?

Well, he likes the camera like everybody else in that position, so I think he'll do it eventually. But what's really important about what he did was that he has a very significant chunk of the vote in New Hampshire. Now that that's gone, that vote's not going to Trump. So it's either going to go to Haley, who is surging, or to DeSantis, who is floundering. So I think it's really going to help her significantly in New Hampshire. It might put her off at the top if you look at the numbers. I think I wouldn't be surprised to see him come out and endorse somebody if you think it's going to help that person or help them to feed Trump. It's going to be very interesting after Iowa. But Iowa is going to be the bellwather for DeSantis. If he doesn't end up in second place in Iowa, I think he's in real trouble. If he ends up in second place, he lives a fight another day.

Of course, Donald Trump decided not to appear on this stage. He instead held his own competing event just five minutes away. He was asked about the idea of exacting retribution from his critic saying, We're going to make this country so successful. We're not going to have time for retribution. And remember this, our ultimate retribution is success. Is a former President's strategy working here, effectively telling his supporters, A vote for me is a vote against the naysayers?

I don't know what is driving a lot of the people to support him, and I respect them for doing that. I think they want the good performance that he had, and they're willing to look the baggage. But I know the President, I know what he did, and I can tell you that retribution will absolutely 1,000% be on his mind if he wins again. That's something that's very troubling. I think what Nikki Haley said tonight, though, about how in an election against Biden, she polls far better than anybody. If she does get, and that holds true, she would bring on not only her to the White House, she'd bring the House and the Senate and state races as well. That's a powerful argument. I think she needs to make that more because that's a very potent argument.

John Katzko, thank you so much for your time. I appreciate it. Sure thing.

Hi, everyone.

George Stephanopoulos here. Thanks for checking out the ABC News YouTube channel. If you'd like to get more videos, show highlights, and watch live event coverage, click on the right over here to subscribe to our channel. Don't forget to download the ABC News app for breaking news alerts. Thanks for watching.