Trump campaign boss Paul Manafort says that the Republican Party is unified heading into the Republican National Convention this week -- but he still can't help picking fights with other Republicans.

It started on Monday with an appearance on Morning Joe in which Manafort bashes Ohio Gov. John Kasich for not attending this week's RNC in Cleveland.

"He's making a big mistake," Manafort said bluntly of Kasich skipping the convention. "He's hurting his state, he's embarrassing his state, frankly."

Manafort also couldn't resist taking a swipe at the Bush family during a press conference in Cleveland.

"Certainly the Bush family, while we would have liked to have them, they’re part of the past, we’re dealing with the future," he said.

This has not gone over so well with key Republicans in Ohio, however.

Ohio GOP chairman Matt Borges put out a tweet saying that Manafort "doesn't know what he's talking about" when it comes to politics in the state.

And one of Kasich's aides let loose on Manafort by noting Kasich's approval numbers in the state are vastly ahead of where Trump's are -- in fact, the most recent Quinnipac poll of Ohio gave Kasich a 58% approval rating:

Despite all this, Manafort said flatly during his news conference on Monday that "the party is unified," which makes it sound as though Republicans who haven't boarded the Trump Train aren't part of the party anymore.