John Kasich: Donald Trump 'Not Prepared' to Be President Kasich unleashed his harshest criticism yet of Trump on "GMA" this morning.

 -- GOP presidential candidate John Kasich unleashed his harshest criticism yet of Donald Trump this morning on "Good Morning America," hitting the Republican front-runner for his controversial comments on abortion, nuclear weapons, the Supreme Court and the Geneva Conventions.

The remarks came after Kasich released a statement earlier this morning saying, "The past 24 hours revealed in the clearest way yet that Donald Trump is not prepared to be President."

“It’s like a panoply of mistakes and outrageous statements," Kasich said, explaining the statement on "GMA." "You know what it is with Donald? It’s just a stream of consciousness.”

Kasich told "GMA" co-anchor Robin Roberts of Trump, "You can't operate like this."

“People say, ‘Why does he stay in the race?’" Kasich said of those who question why he is still running for president, as he trails Trump and Sen. Ted Cruz by hundreds of delegates. "What, am I supposed to get out and leave it to these guys?”

Kasich specifically criticized Trump's statement Wednesday that women should be punished for getting abortions if the procedure were illegal -- a position from which Trump quickly backtracked after he was roundly lambasted -- his openness to use nuclear weapons in Europe, his suggestion that NATO should be weakened, his opposition to the Geneva Conventions, and his proposal that a Supreme Court justice should be willing to investigate the email scandal surrounding Democratic front-runner Hillary Clinton.

"People around the world must be having a field day," Kasich said. "And you know what Donald ought to be happy about is that Jon Stewart's not running 'The Daily Show.'"

He added: "Things that are coming out of Donald’s mouth that are just, they’re just basically irresponsible.”

On a lighter note, Kasich defended using a fork to eat his first bite of New York pizza on Wednesday, a practice frowned upon in the Big Apple.

"The pizza came scalding hot, so I used a little fork," Kasich said. He said his wife was proud of him and told him, "You finally learned how to use a utensil properly."