I have trouble understanding this sentence. Is it "These are candidates for president" or "These are the candidates proposed by the president". Or maybe it would sound the same and depends on the context?
Although I understand both of your possibilities, I think the former would be the context that most people would automatically think of.
"Esses são os candidatos presidenciais." Pode ser? Se sim, qual é a diferencia?
It's a problem involving "this, that, ..." and they keep mixing it up. Further information: http://www.duolingo.com/comment/536217
"Esses" is now accepted.