Former Clinton adviser and Democrat pollster Mark Penn applauded Nikki Haley's performance at the first Republican presidential primary debate, telling "The Brian Kilmeade Show" Thursday that the former U.N. ambassador would be best suited to lead the State Department under a Republican White House. 

STEPHANOPOULOS SNAPS AT NIKKI HALEY FOR SAYING BIDEN WON'T FINISH HIS TERM: 'EXCUSE ME... HOW DO YOU KNOW?'

MARK PENN: I think there was no definitive winner. I think that there are four candidates –  look, I think the DeSantis did well enough, right? He can go back to his camp. He's not a champion debater but he did stick to his record. I thought Nikki Haley showed real foreign policy experience. I thought Tim Scott, you know, did really well in terms of, you know, his kind of belief in the American dream. And Ramaswamy, you know, controversial, but I have to keep him in the top four. So I thought Nikki Haley really came after him quite effectively on foreign policy. And then the rest, frankly, you know, I think aren't going anywhere. 

I thought if nothing else, [Haley] definitely won secretary of state last night. She showed foreign policy, you know, experience and knowledge far above anybody else. 

Haley alleged on the GOP debate stage Wednesday night that Russian President Vladimir Putin killed Wagner mercenary chief Yevgeny Prigozhin, tearing into political newcomer Vivek Ramaswamy for "choosing a murderer" over pro-American Ukraine.

Haley argued Ramaswamy, who claims the U.S. is "driving Russia further into China’s arms" by giving billions to Ukraine, wants to "hand Ukraine to Russia" and "let China eat Taiwan."

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"You don't do that to friends. What you do instead is you have the backs of your friends. Ukraine, it's a front line of defense," Haley said in Milwaukee. "Putin has said… once Russia takes Ukraine, Poland and the Baltics are next. That's a world war. We're trying to prevent war. Look at what Putin did today. He killed Prigozhin. When I was at the U.N., the Russian ambassador suddenly died. This guy is a murderer. And you are choosing a murderer over a pro-American country."

Fox News' Danielle Wallace contributed to this report.

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