I would say that is "someone that can change things at the stroke of a pen", don´t know if there´s an exact equivalent translation.
Now, there are other expressions (not exact ones) that would do: the powerbrokers (beware the context, though), the powerful (ones) etc.
I mean, depending on the person or group you are referring to, you can mention in English e.g.: the powerbrokers/the powerful, the power-holding group, ,etc... Could be translated as "aqueles com o poder da caneta". It might have an exact translation, but I don´t know of, so I´ll leave it to other more on the know, people of English-speaking countries, etc.