What are the key elements of a clever campaign slogan?

Good campaign slogans are generally brief, appeal to the emotions of the target constituency and reinforce patriotic ideas about being united with people who are on the right side of history. Good policy appeals to the largest constituency, not only the ones a candidate agrees with.

If a candidate in an area where abortion is a contentious issue, and the largest constituency is basically using abortion as a litmus test for political legitimacy, a good example for a female politician's slogan is, "Jane. A Mother You Can Trust." Because the slogan uses "mother," which both implies she did not have an abortion and connects her with other mothers who are voting, it is a good slogan.