The seven years war changed the balance of power in north america after the Peace of Paris in 1763. Britain’s debt was enlarged, forcing them to tax the colonies. They expanded their territory in the New World: they gained former French lands and Spain gained other French lands.
Voting as a partisan can be an effective way to mobilize your constituents to keep voting for you, as long as you don't engage even more partisan wings of your party.
Unlike moderates or people who compromise, partisans don't have the ability to draw new members into their coalition, unless new people see their way of thinking.