Actually the above posters are right that suburban whites fleeing Massachusetts helped push the state to the Right in the 80's and 90's. While the orther Northern New England States like Vermont and Maine were left relatively unchanged and have since moved much farther to the left then New Hampshire if anything New Hampshire moved in the opposite direction, towards the GOP. The continued trends among Native New Hampshire residents, migrants from other states, and Canada have since 2000 moved the State to the left.
Neither are libertarian. Maine is a socially Liberal, economically moderate to populist state. New Hampshire is a fiscally conservative(but decreasingly so) socially moderate state. If the GOP in Northern New England could somehow seperate itself from the National GOP they could indeed restore some modicum of success in Maine, New Hampshire, and even in Vermont.
The Republican Party in Maine seems pretty strong. They have 2 Republican senators (albeit very moderate ones).