Pennsylvania Senator John Fetterman broke ranks with Democrats ahead of Tuesday night's high-stakes debate, conceding that Kamala Harris will face off with a "good debater" in Donald Trump.

“It’s going to be a straight-up debate,” Fetterman told CNN’s State of the Union.

“She’s going to do great, of course, but Donald Trump will be good too. I mean, we can all remember he wrecked all of the Republicans. He’s a good debater,” Fetterman added.

"It's going to be close"

With no additional matchups lined up between Trump and Harris, Tuesday night's debate could have a big impact on a very close, and unusually short presidential contest, which was reset this summer in an unprecedented shakeup.

Fetterman was a notable supporter of Joe Biden after his disastrous June debate, which led him to end his re-election bid under pressure from his party. While Fetterman supports Harris now, he maintains that Biden would have beaten Trump.

“I do believe fundamentally that Joe Biden would have beaten Trump, and it was going to be very close, and I have always predicted that as well too, and now Harris,” Fetterman said.

Meanwhile, there are signs that Harris' '"honeymoon" is over, with a sobering New York Times poll Sunday showing Trump ahead nationally.

Still, Fetterman disagreed with those who see the ABC News debate as a make-or-break moment, maintaining the presidential race will be "close" no matter what.

“At the end of the day, I don’t believe this debate’s going to be definitive because it’s going to come down to this choice, and it’s going to be close,” he said.

Kamala = order?

Trump is said to be making little formal preparation for the debate outside of discussing policy with his aides. Harris has taken a more intensive approach at a hotel in Pittsburgh, spending hours in mock debate sessions.

Ultimately, Fetterman believes voters in Pennsylvania will reject Trump's "chaos" and choose "order."

"I think a majority of Pennsylvanians are going to decide, ‘Hey, I want four years of order and fairness and unity and a different way forward.’ And I don't think they want the kinds of dark days and chaos that Donald Trump provided for our nation," the senator said.

Trump is a formidable debater indeed, a one-of-a-kind opponent. If Harris turns to an anxious mess and starts spewing "word salad" on national TV, it will be hard to sell her as the candidate of "order."