The emergence of foreign policy as a central issue in the presidential campaign poses the greatest threat to Ben Carson — no other GOP candidate has as much vulnerability on the issue.

That’s according to the overwhelming majority of Republican insiders surveyed this week by The POLITICO Caucus — a bipartisan panel of the top strategists, operatives and activists in the four early nominating states: Iowa, New Hampshire, South Carolina and Nevada…

“Ben Carson’s complete ineptitude makes you long for the days of ‘Uz-beki-beki-stan-stan,’” added an Iowa Republican, referring to a disastrous Herman Cain interview four years ago…

“Carson is so clueless,” said an Iowa GOP insider. “He thinks the Kurds are a special kind of Wisconsin cheese.”