Washington (CNN) Democratic Sen. Cory Booker, who has made party unity a major theme of his presidential campaign, on Wednesday admonished his rivals for launching "personal attacks" during the fourth primary debate, saying if the candidates cannot stay unified, they won't be successful in "trying to unify the nation."

"It's fine to delineate your differences with other primary candidates. But the way we do it matters. It cannot be personal attacks, tearing folks down, doing so in a way that wounds us as a party," Booker told CNN's John Berman on "New Day." "At the end of the day, we have to show that unity that's necessary to develop the kind of strength it needs to beat Donald Trump."

"If we can't unify the Democratic Party, you're not going to have a great success in even trying to unify the nation," the New Jersey senator added.

On Tuesday night, Booker joined 11 other candidates at the fourth Democratic primary debate, hosted by CNN and The New York Times in Westerville, Ohio. The debate was marked by increasing aggressiveness among the different candidates, who are all looking to break out as the contest inches toward 2020. In particular, Massachusetts Sen. Elizabeth Warren faced attacks by a number of her rivals who were looking to take shots at her now that she is a front-runner in the contest. At one point during the debate, South Bend, Indiana, Mayor Pete Buttigieg accused Warren of dodging a yes-or-no question, and Minnesota Sen. Amy Klobuchar accused her of being dishonest.

"Last night (Warren) was more specific and forthcoming about the number of selfies she's taken than about how (her 'Medicare for All') plan is going to be funded," Buttigieg told CNN's Alisyn Camerota on "New Day" Wednesday.

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