The degree of polarization that currently exists in Washington is such where I think it's fair to say if I presented a cure for cancer, getting legislation passed to move that forward would be a nail-biter.

That's part of what I tried to describe to my team and supporters after the election, there was a lot of disappointment.

It's important to listen to what scientists have to say, even when it's inconvenient, especially when it's inconvenient

This is American leadership at its best: We stand with people who fight for their own freedom, and we rally other nations on behalf of our common security and common humanity.

You don't know how it would have turned out if [kids] would grown up in Chicago instead, and a more normal environment.

When it comes to preventing Iran from obtaining a nuclear weapon, I will take no options off the table. ... That includes all elements of American power: a political effort aimed at isolating Iran, a diplomatic effort to sustain our coalition and ensure that the Iranian program is monitored, an economic effort that imposes crippling sanctions and, yes, a military effort to be prepared for any contingency.

We seem to have trouble with [critical thinking]. And our political system doesn't help.