The correct answer to this open question is the following.
Although there are no options attached, we can answer the following.
In this sentence, the phrase "without violating the principles to which he is attached" most likely refers to the faction one citizen supports.
We are referring to Federalist 10, written by Federalist James Madison under the pseudonym of "Publius."
A faction is conformed by a group of people with personal agendas that have a particular interest. They only work for the benefit of their faction or against other factions. Sometimes they stepped onto another in order to get what they wanted. That is why people like James Madison wanted to form a Republic. To look for an entire nation, for all people´s necessities. He believed that with the creation of a Republic, factions could be controlled.