Kasich vows Trump won't be nominee
© Fox News

Ohio Gov. John Kasich is refusing to say whether he would endorse fellow GOP candidate Donald TrumpDonald John TrumpConservatives express concern over House GOP immigration bill Poll: McSally holds 14-point lead in Arizona GOP Senate primary Trump defends Nielsen amid criticism over family separations MORE if the billionaire becomes the Republican nominee for president.

"He's not going to [be the nominee]. So we're not even going to go there," Kasich said on ABC’s "This Week with George Stephanopoulos."

All the other Republicans running for president have publicly declared that they will support the party's eventual nominee, but Kasich -- whose super-PAC is running the toughest attack ads against Trump -- is unwilling to say that he would support the GOP front-runner.

Pressed repeatedly on Sunday by moderator Martha Raddatz on whether he would support Trump if the real estate mogul becomes the Republican presidential nominee, Kasich continued to deflect the question.

"He's not going to be the nominee... because, at the end, look, he may have 20 percent of the vote," Kasich said. "But he's got 80 percent of Republicans who don't support him. And somebody has to call him out on this kind of divisive language."

"I think he's very divisive and I do not believe he will last," Kasich added.

"Because somebody who divides this country here in the 21st century, who's calling names of women and Muslims and Hispanics and mocking reporters, then say I didn't do it but he did do it, it's just not going to happen."

Trump has been leading the GOP polls since July and his support has sustained throughout numerous predictions of collapse by media pundits.