On the spectrum of successful politicians, I'm not introverted the way some have been.

We are engaging in the diplomatic efforts that are required within Iraq among the Shia, the Sunni and the Kurd, among friends, like Egypt, and Turkey and Saudi Arabia, but also enemies like Iran and Syria. They have to have buy-in into that process.

One of my strengths is I have a pretty even temperament. I don't get too high when it's high and I don't get too low when it's low. And what I found during the course of the presidency, and I suppose this is true in life, is that investments and work that you make back here sometimes take a little longer than the 24-hour news cycle to bear fruit.

We are now at a point where because we in fact have been successful at stopping a number of plots, a threat has evolved. We do see these lone-wolf actors. We do see these encouragements for troubled individuals to pick up a gun and act out of this ideology.

If you're a progressive, you've got to be worried about how the federal government is spending its revenue, because we don't have enough money to spend on things like early childhood education that are so important.

I think we should all hope for a Russia that is successful, where its people are employed and the economy is growing and they are having good relationships with their neighbors.

There's one issue that will define the contours of this century more dramatically than any other, and that is the urgent and growing threat of a changing climate.