Donald Trump's behavior since the Republican convention last month has made John Kasich less likely to endorse him and caused the Ohio governor to experience "a little grief."

"I've had a lot of people pound on me about, you need to do this, you need to do this, this is about the party," Kasich told CNN's Jake Tapper in an interview aired Sunday. "And I love my party, but I love my country. And I have to be true to myself. I wish that I could be fully enthusiastic. I can't be."

Kasich, who declined to attend the GOP convention and has been a vocal critic of his party's presidential nominee, has yet to determine how he will cast his ballot on Nov. 8.

"[I get] a little grief over this," said the ex-White House hopeful about the process of deciding which candidate to support. "I don't know what's going to happen at the end.

But Trump's recent confrontation with the parents of a fallen Muslim-American Army captain and his latest attacks against Democratic presidential hopeful Hillary Clinton has put Kasich in an even tougher position, the two-term governor told CNN.

"There's so much water over the dam now, it's become increasingly difficult," Kasich said. "But I want, you know, unifying."