Donald Trump believes Hillary Clinton's refusal to use the phrase "radical Islam" is evidence she's playing nice with President Obama to escape punishment for her growing email scandal.

"We have a president who refused to use the term the other day and of course, [Clinton] is concerned that if she angers the president she's going to end up being indicted," the Republican presidential hopeful told supporters in Spartanburg, S.C., Friday.

"She's walking on eggs right now — bom bom bom," Trump said, while using hand gestures to pantomime a walking motion.

"So, you know, she has to be very nice. She has to behave very nicely," he added.