DES MOINES, Iowa — Presidential candidate Jeb Bush says he once got an e-mail asking if he would go back in time, if it were possible, and kill the baby Adolf Hitler.

“It said, ‘If you could go back in time and kill baby Hitler, would you? I need to know,”’ Bush told a Huffington Post reporter on his campaign bus last week.

Bush’s answer, according to the video clip: “Hell, yeah, I would. Look, you gotta step up man.”

Bush wryly tweeted Monday: “Gotta do it.”

The typically dry-humored Bush, labeled by rival Donald Trump as “low energy,” has shown a more carefree side lately.

Bush has recently been publicizing his new book, “Reply All,” a collection of stories told through the e-mails he received as governor of Florida.