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"You’re not going to get me to answer a yes-or-no question," Kasich said. "I hope he’s going to change his rhetoric and bring people together."
Kasich criticized Trump on Saturday for creating a "toxic environment" that has led to violence at some of his rallies. He had previously pledged to support Trump if the real estate mogul were to win the nomination, but said Sunday that "nothing's 100 percent."
"Sometimes it’s really tough," Kasich added. "I hope to be able to support whoever the nominee is."
Polls show Kasich in a tight battle with Trump ahead of Ohio's Republican primary. A NBC News/Wall Street Journal/Marist poll released Sunday showed Kasich leading Trump 39 percent to 33 percent.
Kasich believes Ohio could be a turning in the race and that if he blocked Trump in the Buckeye State, he could prevent him from becoming the Republican nominee.
“I absolutely believe that," Kasich said. "Ohio always seems to be the geographical center of the political universe."