The article in question. I had a teacher mention this in class and I decided to do some fact checking. I've tried the standard google searches and can get no references, so I'm wondering whether it's a made up example or an actual event.
The earliest source I could find was the biography of George Perkins, "Right-Hand Man", page 274.
In which there is the following disclaimer regarding the source: "Since there are no copies of these telegrams in the Perkins papers one must rely on Davis's recollection of them, as printed in his memoirs. Probably, therefore, the wording reproduced here is not completely accurate. For a print of the photograph in question, bearing the Moffett copyright, see the cover of the first issue of the Progressive 'Bulletin."
I couldn't find the "O.K. Davis memoirs" referenced here but it doesn't sound like it would provide much more information at this point.
EDIT: Found the Davis memoir. Titled "Released For Publication", page 341 details the story, and as expected, no information was added (except for Perkins' response). Still though, if it was an invented story, at least it's an old one by someone who was working for the campaign in question.