CHUCK TODD:

Last week with me, Secretary Clinton said when it comes to party unity, she's doing her part, she's going to do her part. But that there is a responsibility that falls on you as well. If she's the nominee, that you have a responsibility to do what it takes to bring your supporters on board with her. Do you accept that responsibility?

BERNIE SANDERS:

Well, the responsibility that I accept in a very, very serious way is to do everything that I can to make sure that Donald Trump will not become elected president of the United States. Donald Trump, for a dozen different reasons, would be a disaster as president. I will do everything that I can to make sure that does not happen.

But at the end of the day, whether it's Secretary Clinton or Bernie Sanders or Donald Trump, anybody else, the way you gain support is through the candidate himself or herself. So my job is to make sure that Trump does not become president. And I will do that. But if Secretary Clinton is the nominee, it is her job to reach out to millions of people and make the case as to why she is going to defend working families and the middle [class], provide health care for all people, take on Wall Street, deal aggressively with climate change. That is the candidate's job to do.