Na versão americana publicada pela Scholastic Press no capítulo onze, há o texto:
Ron and Hermione joined Neville, Seamus, and Dean the West Ham fan up in the top row. As a surprise for Harry, they had painted a large banner on one of the sheets Scabbers had ruined. It said Potter for President, and Dean, who was good at drawing, had done a large Gryffindor lion underneath. Then Hermione had performed a tricky little charm so that the paint flashed different colors.
e algumas linhas depois:
Out of the corner of his eye he (i.e. Harry) saw the fluttering banner high above, flashing Potter for President over the crowd. His heart skipped. He felt braver.
Irritantemente, minha sobrinha tem minha edição no Reino Unido, então não posso verificar isso - alguém pode verificar para ver o texto que tem?
De qualquer forma, eu não acho que haja um grande significado para a frase "Potter for President". É apenas um incentivo para Harry, e de fato funcionou.