I believe marriage is between a man and a woman. I am not in favor of gay marriage. But when you start playing around with constitutions, just to prohibit somebody who cares about another person, it just seems to me that's not what America's about. Usually, our constitutions expand liberties, they don't contract them.

The arc of the moral universe may bend towards justice, but it doesn't bend on its own.

One of the things that you learn, having been in this [President's] office for four years, is the old adage of Abraham Lincoln's. That with public opinion there's nothing you can't do and without public opinion there's very little you can get done.

Based on current surveys of public opinion in the United States, it turns out that the majority of Americans think I've done a pretty good job.

Climate change constitutes a serious threat to global security.

Trayvon Martin could have been me 35 years ago.

And yes, my plan will continue to reduce the carbon pollution that is heating our planet - because climate change is not a hoax. More droughts and floods and wildfires are not a joke. They're a threat to our children's future. And in this election, you can do something about it.