Story highlights Jeb Bush lacks confidence in Donald Trump's ability to handle nuclear weapons

Bush says Trump will not be the Republican nominee

Washington (CNN) Jeb Bush said Donald Trump discusses foreign policy like a reality show star and that support for the Republican front-runner will eventually wane.

Bush also said he has little confidence in Trump's ability to appropriately handle America's nuclear weapons.

"I have grave doubts, to be honest with you," Bush told CNN's Jake Tapper in an interview airing Sunday on "State of the Union."

"He's not taking the responsibility, the possibility of being president of the United States really seriously. For him, it looks as though he's an actor playing a role of the candidate for president. Not boning up on the issues, not having a broad sense of the responsibilities of what it is to be a president," Bush said. "Across the spectrum of foreign policy, Mr. Trump talks about things as though he's still on 'The Apprentice.'"

Bush said Trump's proposed plan of hoping ISIS removes Syrian President Bashar Assad from power and then Russia taking on ISIS is like "some kind of board game and not a serious approach."

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