Too bad he didn't get his buddy Viktor Yanukovych to headline and talk about how he made Ukraine great again.
I understand Manafort's frustration but, with this talk, he is going to make the situation only worse. He needs Kasich and the Ohio GOP to make Trump even remotely competitive in November. If the Trump campaign really wants to move the needle, they should offer policy concessions to Kasich and the Ohio GOP and try to get them to help. But this is Trump and the politics of entertainment, so it won't happen.
If the US politics wasn't so polarized, Clinton could do worse than use the GOP rift, and offer the VP slot to Kasich.