Kennedy ended his speech with this: "For me, a few hours ago, this campaign came to an end. For all those whose cares have been our concern, the work goes on, the cause endures, the hope still lives, and the dream shall never die." There wasn't a dry eye in the old Madison Square Garden, and the ovation that followed was thunderous.
I have a theory that politicians are at their rhetorical best when they lose an election. It's hard to say exactly why this is the case. Perhaps it's because the pressure of always being "on" no longer matters, or perhaps because they can simply relax and be themselves. In any event, the result is that they allow us to see the best in them as they exit the fight.
If I were advising a political candidate in 2024, I would counsel them to imagine they had just lost the campaign, then speak to the voters with the humility and honesty that loss would bring. That "loser" mentality might just result in victory.