“Governors can certainly read about foreign policy, and take meetings and briefings with experts,” the Florida Republican said, “but there’s no way they’ll be ready on Day One to manage U.S. foreign policy.”

At an afternoon reception put on by Iowa Republican congressman David Young, the Wisconsin governor and prospective presidential candidate struck back.

“Sometimes people say, ‘How can a governor talk about foreign policy?” Walker told the crowd at the Machine Head restaurant in West Des Moines. “In my lifetime, the best president when it comes to foreign policy was a governor from California. In my lifetime, the worst president for foreign policy was a freshman senator from Illinois.”