Barack Obama: “When I'm President, we're not going to gamble with Social Security.”

helped lead some of the most significant movements for change in human history

It fortifies you to say that, yes, this has been part of the journey that we’re on.

They're meant to remind us of who we can be, to remind us of what's possible, so we can forge ahead.

Every president here today, as different as we are, has tried our best to uphold the values that John McCain and Mitt Romney believed in no less than I did.