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Story highlights

John Kasich spoke at a news conference in New York

He detailed why voters should back him and not GOP front-runner Donald Trump

(CNN) —  

On Donald Trump’s home turf John Kasich on Thursday tried to limit his number of reasons why GOP primary voters should reject the billionaire businessman.

“I had to list five things that continue to prove that Donald Trump is clearly not prepared to be President of the United States, commander in chief, leader of the free world,” Kasich said in opening a New York news conference.

Kasich sought to take the offensive against Trump, who of late has largely avoided attacking the Ohio governor, instead pointing most of his fire at Ted Cruz. Earlier in the race Trump attacked Kasich over negative ads, his position on trade and for being an “absentee governor.”

On Thursday, though, Kasich didn’t limit himself to five reasons, hammering Trump on a range of fronts. Here are some of his sharpest jabs.

– “As a commander in chief and leader of the free world, you don’t get do-overs. You need to be able to get it right the first time.”

– “We know about his comments on abortion, which would put women in a very difficult position. And we know that he has since moved to correct those in one way or another.”

– “He actually talked about the use of nuclear weapons both in the Middle East and Europe. You wonder about his hand or his thumb getting any close to the critical button that presidents are in charge of.”

– “He says we should basically abolish the Geneva Convention, which was created to make sure that we had fair treatment for anybody who could be captured in war and that somehow we ought to abolish the Geneva Conventions and engage in, I guess, more torture, which doesn’t sit well with any of the people who have served our country so honorably, like (Arizona senator and former prisoner-of-war) John McCain.”

– “He’s called on NATO to basically be abolished although I can’t figure out what his position is today. I happen to believe that NATO needs to be strengthened and turned from basically solely a military organization into an intelligence and policing organization that can work across borders.”