“What makes me cautiously optimistic about my successor and the shift from campaign mode to governance is there’s something about the solemn responsibilities of that office, the extraordinary demands that are placed on the United States -- not just by its own people but by people around the world -- that forces you to focus, that demands seriousness. And if you’re not serious about the job, then you probably won’t be there very long because it will expose problems. Even when you’re doing a job, even when you are attentive, there are so many things that come across your desk that people are going to question you, and you’re going to have opponents and you’re going to have critics, and you figure that out pretty fast when you’re sitting there.  And I think the President-elect is going to see fairly quickly that the demands and responsibilities of a U. S. President are not ones that you can treat casually, and that in a big, complex, diverse country, the only way that you can be successful is by listening and reaching out and working with a wide variety of people.”

2016, News Conference With Chancellor Angela Merkel of Germany (November 2016)