In an interview with CNN's Jake Tapper on "State of the Union," Kasich, a Republican presidential candidate, said he isn't buying polls that show Trump in the lead -- including a new CNN/ORC poll
that puts the real estate mogul's support at 36%, more than double any other contender, among Republicans.
"I don't necessarily believe what I see because it's not a poll of likely voters," Kasich said, adding that he's not convinced many of those who say they support Trump will ultimately vote for him.
Kasich also defended his ad featuring a former U.S. prisoner of war, Col. Tom Moe, which some have said recalls the famous poem "First they came ..." written by Pastor Martin Niemöller about Nazis, while highlighting groups Trump has attacked.
The Ohio governor denied the ad was meant to compare Trump to Adolf Hitler, but defended the tenor of the ad.
"When you attack Hispanics, when you characterize all Muslims in a negative way, when you insult women, we don't think that that's good," Kasich said. "We think, at this point in time more than any other time, we need to have America united, and we need to have an American president that's going to unite us and not divide us."
Former Florida Gov. Jeb Bush also predicted Sunday that Trump won't win the GOP nomination -- even as he acknowledged Trump's political skill set in an interview on ABC's "This Week."
"He's succeeding right now for sure. He's a gifted politician. But he's not a serious candidate. He's not offered anything serious as it relates to the fight against terror. He's not offering any proposals as it relates to dealing with these structural challenges we face going forward," Bush said.
"But he's a gifted politician," he said. "He connects with people's angst and their anger. But over the long haul, we need to have productive, constructive ideas to lift people up."