MIAMI — The Republican front-runner for the presidential nomination, Donald Trump, is not prepared to be the nation’s commander in chief, because he’s “uninformed” on major issues facing the U.S, especially defense and foreign affairs, rival Jeb Bush said on Sunday.

“I have great doubts about Donald Trump’s ability to be commander in chief,” Bush said on CBS’ “Face the Nation.” “If you listen to him talk, it’s kind of scary to be honest with you, because he’s not a serious candidate.”

Bush said Trump has offered conflicting opinions on his strategy to deal with Syria and the Islamic State group.

Trump “said we had no interest in being involved in Syria. And then he said let the Russians take out ISIS. And then he said let ISIS take out Assad. I just think he’s uninformed,” Bush said, using an alternative acronym for the Islamic State group, also known as ISIL.

Bush’s criticism of Trump comes a day after the billionaire businessman campaigned in the former Florida governor’s home state and dismissed Bush as a serious challenger.

Trump told thousands at a rally in Sarasota, Florida, on Saturday that he would easily win the March 15 Florida primary because “I’m leading by a lot already.”