Donald Trump’s chief adviser Paul Manafort’s negative comments about Gov. John Kasich won’t help his chances of winning the swing state in November, according to Ohio GOP Chairman Matt Borges Monday.

Manafort said at a breakfast in Cleveland during the Republican National Convention that Kasich, who ran against Trump in the primary, was “embarrassing his party in Ohio” for opting against endorsing the billionaire.

“He’ll need to do better if we’re going to carry Ohio in the fall,” Borges told Politico.

He said Trump was failing to accomplish the GOP’s goal of unifying the party, adding he is sure he will acknowledge the “mistake” in the future.

Despite signing a pledge promising to support whoever wins the nomination, Kasich has yet to throw his support behind the candidate.

Kasich’s advisers told U.S. News and World Report he doesn’t not plan to come out against Trump during the week of the convention in an attempt to avert being perceived as “rude.”

“Could he win without the governor’s support? I certainly think that is possible. If they choose to continue on this divisive type of message, it’s going to make things more difficult,” Borges told the publication.

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