In 1904 William Jennings Bryan was still very popular, and still very young, at 44 he left office earlier that any other man had come into the office. Many people were pushing for him to do so, but WJB refused. He still influenced the Democrats long after he left and until his death.
But lets say he felt he had to, assisting out the newly-independent Cuban and Philippine Republics took much longer after he left office, if he felt whoever succeeded him would be insufficient to helping them, or even annexing them as many Republicans wanted, would/could he win?