In his speech to the Clinton Global Initiative:

When I was in business, I traveled to many other countries. I was often struck by the vast difference in wealth among nations. True, some of that was due to geography. Rich countries often had natural resources like mineral deposits or ample waterways. But in some cases, all that separated a rich country from a poor one was a faint line on a map. Countries that were physically right next to each other were economically worlds apart. Just think of North and South Korea.

I became convinced that the crucial difference between these countries wasn’t geography. I noticed the most successful countries shared something in common. They were the freest. They protected the rights of the individual. They enforced the rule of law. And they encouraged free enterprise. They understood that economic freedom is the only force in history that has consistently lifted people out of poverty – and kept people out of poverty.

I guess someone on his staff read a synopsis of Acemoglu and Robinson.