Most of the time, when we think of the President, we think of him as the leader of his party. It's only natural; most of the time he is- after all, people run for President so they can do things, and use "the bully pulpit" for that purpose.
But there are other times... rarely, at times of national pride and accomplishment, like the Moon landing; more often during times of heartache, when we really need the president to be The President of the United States. And there is something about being President that affects the occupant of that office, something that elevates them to another plane of performance at those moments- no matter who they were before, or who they will be after, they become in that moment the archetype we carve into the sides of mountains. They become my President, our President. It happened last night, at the memorial in Arizona.
Here is the finest moment, an ad lib, added to the prepared speech at the last minute: