“If you view it as a serious proposal, which it isn’t, what he’s proposing is weakening our position in the world,” Bush said, “making it harder for us to be protected. Not stronger. He’s weakening the United States’ posture in the world, and he’s keeping our country less safe.”

Business Insider asked if that was the case already. Bush said Trump’s statement alone was detrimental to the US’s foreign-policy interests.

“By his statement!” Bush said. “If that statement was to be a policy and was implemented, it would make it harder for us to take out ISIS. Near impossible. It would make it harder for us to engage in the world. No one would take us seriously. This is ludicrous. This is not even worth talking about.”

But American voters, at least, think it might be worth talking about. Some surveys have nevertheless shown a surge in support for the front-running Trump after his inflammatory comments.

Bush’s own town-hall event was full of voters sympathetic to Trump’s point of view. One voter — who wouldn’t give his name for a lack of trust in the media — said he wished to see Bush discuss what he perceived as problems of violence within Islam.