I want to reform the tax code so that it's simple, fair, and asks the wealthiest households to pay higher taxes on incomes over $250,000 - the same rate we had when Bill Clinton was president; the same rate we had when our economy created nearly 23 million new jobs, the biggest surplus in history, and a lot of millionaires to boot.

I wonder, sometimes, whether men and women in fact are capable of learning from history--whether we progress from one stage to the next in an upward course or whether we just ride the cycles of boom and bust, war and peace, ascent and decline.

Now is not the time to gut these job-creating investments in science and innovation. Now is the time to reach a level of research and development not seen since the height of the Space Race.

Where you are right now doesn't have to determine where you'll end up.

We are committed to a world in which we keep America safe, but we recognize that our power doesn't just flow from our extraordinary military but also flows from the strength in our ideals and our principles and our values.

I think it's fair to say that [Donald Trump] and I are sort of opposites in some ways.

There are institutional obligations I have to carry out that are important for a president of the United States to carry out, but may not always align with what I think would move the ball down the field on the issues that I care most deeply about.