As near as I can tell from the record, the presidents before my lifetime were well aware of being the leader of all Americans and responsible to them, whether they hated him or not. It was part of the expectations of the job. Similarly, the citizenry regarded the officeholder as their president, however furious they might be with him. Perhaps I have understood history wrongly, but that seems to have been the case.
Truman's presidency ended just before I was born, and I was not aware of political matters during all of Eisenhower's time. But the memory of others around me was yet green and much of the record has always been available. They seemed aware of being president of all Americans, even those who disagreed with them. Kennedy biographers, even those quite critical, reveal a man who likewise carried that expectation of himself.
Johnson arrived with a deeply partisan reputation, and later in his second term was vilified by many on the left. Yet he rose entirely to the public expectation of responsibility to all, even while he was arm-twisting for legislation. At that point the citizens began to drop their end of the bargain. Somewhere in that time the left began shading over from "I am furious with my president" to "He is not my president." Those on the right who were angry may not have abated in their fury, but conservative culture did not foster that kind of abandonment.
I remember something about the campaigns of '60 and '64, but not the tone of the candidates. Campaign mode is a little different, and rather more oppositional, us-them speech is appropriate there. I remember Nixon the campaigner injecting quite a bit of an attitude of Our Americans as opposed to Not-Quite-Americans. In his defense, many of his critics were fully in that mode, having taken the next step from the Johnson era and defined themselves in terms of a loose "Westernism" that included American liberals and much of Western Europe. Further, after the campaigns were over Nixon did seem to elevate to the expectation somewhat. He clearly saw himself as president of "the bulk of Americans."
Yet something was lost here, and Nixon seems to have started it. (Or is it just my hippie memory that thinks so?)
Ford was determinedly president of all, and though Carter had some tendency to promote divisiveness for his ends, he comes out clean here. He saw himself as the leader of the nation, not of the Democratic Party, even to those who hated him.
Reagan had some oddities when measured on this scale. He brought Nixon's president-of-90%-of-Americans attitude when speaking generally, but in his actual interactions with people, including opponents who despised him, he remained gracious. He could even become starry-eyed about the presiding over the 90%, and in all international dealings, it rose to 100%. That last hearkens back to a much older tradition. But the American people were more used to the not-my-president approach at this point and his opponents were more open about this than had been true even under Nixon.
Bush 41 never dropped his responsible-to-all attitude, whether his polling was good or bad at the moment. The country was as divided under him as it was under any of the others I have named. Memories are short. During his son's term people would believe they recalled a different America under 41, when people could disagree with their president but still respect him. They forget or they lie. The left hated Bush 41 at the time and were quite open in their regarding him as a second Reagan, who they did not acknowledge as their leader.
Clinton, who initiated the permanent campaign, stayed in campaign mode in tenor as well. While he frequently rose to the higher expectation of how a president is to represent the people, he just as often fell to an attitude of "I am representing the good Americans in their battle against the bad ones." What Nixon had started and Reagan engaged in, Clinton increased and made his default position. Something new happened in the citizenry here as well. Elements of the right began to speak in terms of not-my-president. This is a sentiment against some of their central values, so it never caught on fully. But it appeared for the first time and even had some eruptions during Bush 43's terms.
Those who opposed Bush 43 will scramble to find some way to show that the following is not true, because to acknowledge it would be expensive. But Bush returned the presidential attitude to something near that of his father. He was conscious of his responsibility to the entire nation, even when they were vilifying him. Interesting evidence of this is in how far his opponents had to scramble to even find things they could twist into divisiveness. "You're either for us or against us" didn't have the meaning they pretend even when referring to other nations. It had none in referring to Americans. No matter. It fit what people wanted to believe about him.
Obama seems to still be in campaign mode, so there is a lot of data left to accumulate on him. His campaign is now switched from his person to his agenda, and one is tempted to cut him a little slack on that basis; but how is that different from any other new president? The early results are very disquieting. Far more than Clinton, Obama remains in "leading the good Americans against the bad ones" mode. He had barely a kind word for the flood victims, and nothing but complaining about other people regarding the oil spill. He complains about Americans to other countries.
Conservatives complain that we are seeing a re-enactment of the Carter presidency in Obama. Sorry, but I can't imagine Jimmy Carter doing this. Nor Bill Clinton even when most beleaguered. We are in new territory here. And on the right, not-my-president, an idea that was previously anathema, is spoken out loud.