Donald Trump’s top campaign adviser accused Ohio Gov. John Kasich of “embarrassing” his home state by avoiding the Republican convention, opening the gathering with a stark display of party disunity.

“John Kasich is being petulant,” Manafort told reporters Monday morning at a Bloomberg breakfast.

Manafort also drew Ohio Republican Sen. Rob Portman into the dispute, saying Portman is “very upset” with Kasich and believes the governor’s lack of support for Trump is hurting his own re-election campaign. Portman is locked in one of the year’s toughest Senate races and is grappling with how closely to align himself with his party’s presidential nominee.

Portman’s campaign quickly disputed the idea of a rift between the Ohio senator and governor, who are longtime friends and colleagues.

“That’s totally false,” said Corry Bliss, Portman’s campaign manager. He added that Portman and Kasich are “working hand in hand” on the senator’s campaign and “any suggestion otherwise is inaccurate.”

Trump has been a divisive figure in the Republican Party throughout his presidential campaign. While many top GOP leaders are not attending this week’s convention, Trump’s campaign says it’s still optimistic the party with leave Cleveland more unified.

Trump’s conflict with Kasich, however, threatened to undermine that effort.

Kasich has yet to endorse Trump since ending his own presidential campaign and has no plans to speak at the Republican convention. Still, he plans to spend much of the week in the Cleveland area, meeting with delegations and holding other events.

Portman has said he plans to be on the convention floor occasionally this week, but is not delivering a speech.

Ohio is one of the biggest prizes in the presidential election and almost certainly a must-win for Trump. Ohio, worth 18 electoral votes, has been carried by every winning candidate for president since 1964, and by a margin of less than 3 percentage points in the past four White House elections.

Trump finished second in Ohio’s primary to Kasich.

Portman has endorsed Trump, but is hardly an enthusiastic backer. Like other senators in competitive contests, it’s unclear whether aligning themselves with Trump — a divisive candidate even within his own party — is a help or a hindrance.

Trump’s campaign, however, painted a picture of unity and cooperation with Portman.

“We are working very closely with Rob Portman,” Manafort said. “We’re running our campaign together and he appreciates what we’re doing.”

Ohio Republican Party chairman Matt Borges disputed that characterization.

“Manafort still has a lot to learn about Ohio politics,” he said on Twitter.

(AP)