Barack Obama: “He's the only candidate in this race who has the ability to unite people for real change in our energy policy.”

When we choose, when we make that decision, I do believe – and there is evidence for this – that the world gets incrementally better, and that is a worthy goal and it’s worth fighting for.

A drift towards extremism was "not inevitable

I’m going to insist that we can do better than we’re doing right now.

I think when we act on that basis, it doesn't always work out, but over time things do get better.