Charles Krauthammer reacted on "Special Report" to the announcement of the ten presidential candidates who qualified for Thursday's Fox News-Facebook Republican debate.

Krauthammer said the most interesting, unexpected candidate in the debate - at least as of a month ago - is obviously Donald Trump.

Krauthammer said a more recent surprise, however, is that Ohio Gov. John Kasich made the top ten.

"He came in very late. He holds down the left wing of the GOP. He's a bleeding heart conservative," Krauthammer explained.

He added that another surprise is how Marco Rubio slipped in recent weeks. The Florida senator made the top ten, but he's relatively low, finishing in seventh place, Krauthammer said.

Krauthammer also pointed out that he would have expected Dr. Ben Carson to lose momentum due to Trump attracting all the attention as the "non-politician" of the group, but that didn't seem to happen.

Krauthammer asserted Carson is the tortoise of the race.

"He's slow, he's steady, he's quiet, but he's staying there. And he's got staying power," Krauthammer said.

As for the live forum that will take place before the primetime debate, Krauthammer said he's going to keep an eye on Carly Fiorina and Rick Perry, who could distinguish themselves and end up gaining ground as the campaign rolls on.

Watch more from the "Special Report" panel above.

Don't miss the Fox News-Facebook Republican debate, Thursday Aug. 6, live from Cleveland at 8:50p ET, moderated by Megyn Kelly, Bret Baier and Chris Wallace.

See the 10 Republicans Who Qualified for the Fox News Primetime Debate

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