Now, there were some short-lived comics about Presidential candidates. But these tended to run only a few weeks or months, and were specifically biographic pieces intended to inform/persuade potential voters.
My first thought is perhaps Little Orphan Annie. Creator Harold Gray was fairly open about his politics, and some of his stories sprang directly out of what he saw happening in Washington. In fact, he even killed off Daddy Warbucks at one point because he simply could not fathom a character like Warbucks existing in a country run by Franklin D. Roosevelt! But did any of the Presidents actually appear in the strip? As far as I can tell, no. I'm certainly no Annie expert, but it seems as if Gray only ever even referred to the President obliquely.
My next thought is maybe Li'l Abner. Again, creator Al Capp was pretty outspoken about his politics, and I'm aware of at least a few instances here where he drew real people into his strip as characters. I did pretty quickly find a 1940 strip in which Mammy Yokum receives a letter from the "assistant secretary to the President's secretary". A few years later, the President ostensibly shows up during the Lena the Hyena storyline, but it the figure Capp draws looks nothing like then-President Harry S. Truman. Curiously, Capp draws the judges -- Salvador Dali, Frank Sinatra, and Boris Karloff -- relatively accurately. (Although Karloff is shown in his Frankenstein makeup.)
I was beginning to think maybe Trudeau was the first, but then I happened across this Ernie Bushmiller Nancy where she accidentally phones up John F. Kennedy.
Anyone have any insights on this? Know of anything earlier than 1962?