GOP presidential front-runner Donald TrumpDonald John TrumpAccuser says Trump should be afraid of the truth Woman behind pro-Trump Facebook page denies being influenced by Russians Shulkin says he has White House approval to root out 'subversion' at VA MORE would “get crushed” by Hillary ClintonHillary Diane Rodham ClintonWoman behind pro-Trump Facebook page denies being influenced by Russians Trump: CNN, MSNBC 'got scammed' into covering Russian-organized rally Pennsylvania Democrats set to win big with new district map MORE, fellow Republican candidate Jeb Bush said Sunday.

"Donald Trump, I don’t believe, is going to be the party’s nominee,” Bush told “Fox News Sunday.” “And if he is, he’s going to get crushed by Hillary Clinton. I wanted to point that out.”

Trump, the business mogul who is seen by many voters as a Washington outsider, has surged ahead of the establishment Republican candidates.

He leads the Republican field, with 35 percent support, according to the latest RealClearPolitics average of polls. Bush, at one point, was considered the front-runner, before tumbling from the top of the polls last summer. He now sits at sixth place among GOP candidates, with 4.3 percent of support.

With the Iowa caucuses drawing near, the former Florida governor is turning to attack mode. He accused Trump of being a “strong supporter” of Clinton.

Trump "said some things that are just outrageous,” Bush said. "His views on policy have shifted with the winds. He is a strong supporter, until recently, of Hillary Clinton. And now he’s the front-running candidate for the Republican nomination.

"Someone has to call him out,” Bush added.