I take a different reading. The word mano and it crazy twin - cuate - are a slang terms for buddy in several Latin American countries, so I'd say the portmanteau Ob?manos roughly translates to "Obamabros" or "Obamapals" or "Obamabrothas."
But the best translation I can think for it is "homeys for Obama" or Obamahomeys (Obamaholmes/Obamahomeboys), because it better captures the spirit in which I see it been used, which it to try and connect Obama with Lationos/Hispanic voters - the young ones in particular.
Neologisms are an interesting phenomenon in language and usually formed due to a specific situation, occurrence, event etc. Just imagine it's easy for people living in this era to understand the neologisms that have formed and are forming but a few decades from now people will read these words and will not have a clue what they mean or refer to without research.
In literature, I once came cross the word 'trilce', which is a combination of triste + dulce. The author of his genre and time created the neologism which was a representation of a specific theme and sentiment.