There is a famous saying that ‘politics is the art of the possible.’ As far as it goes that is true, but there are additional P’s to couple with politics, Principle and Priorities and it is these secondary P’s that are often in conflict and often denied for their importance.
Principle is not dogma. Dogma is inflexible. Dogma does not admit the half-loaf and demand only total victory. Dogma demands total fealty. Principle is a guidepost, a map, not a straight jacket.
Priority is about what matters more. If we are being mature about our politics and realistic about our expectations, then priority becomes important and presents us with the most difficult decisions.
For example I support gun rights and I support marriage equality, it is quite rare to find an acceptable candidate that holds both of those positions. Therefore when looking at candidates I end up, via my vote, prioritizing one over the other. In practice it tends to be marriage equality, while I support gun rights I must be honest that it is a secondary cause and that the fight there has to wait while a more important battle is waged.
In my experience most people have the conflicting priorities, but they rarely are honest with themselves in their hierarchy. In my positions they would proclaim themselves both for gun right and marriage equality, claiming the honorable mantle of both camps while ignoring the ground facts of their actual support.