Before I even came into office, I said that preventing Iran from getting a nuclear weapon was a priority.

It is very rare I come to an event where I’m like the fifth or sixth most interesting person.

I do think that when you go into red states, they're - so-called red states - I think they're troubled with certain excesses with respect to the Patriot Act, but they're also concerned with making sure we're secure against terrorism.

We made America more respected around the world, took on the mantle of leadership in the fight to protect this planet for our kids, and much, much more.

We were very effective, and I was very effective, in shaping public opinion around my campaigns. But there were big stretches, while governing, where even though we were doing the right thing, we weren't able to mobilize public opinion firmly enough behind us to weaken the resolve of the Republicans to stop opposing us or to cooperate with us. And there were times during my presidency where I lost the PR battle.

To me the question right now is: How do I close that first three-quarters of the achievement gap, education gap, wealth gap? What gives me the best chance to do that? And I'm pretty darn sure that if America is a just society and treating people well right now, irrespective of past wrongs, that I'm going to close a big chunk of that gap. I've seen it.

No challenge poses a greater threat to future generations than climate change.