BHA, TRCP, and orgs similar to Montana Wildlife Federation in other states.
Hard to support BHA absolutely with Land Tawney at the helm and some of the questionable partners but I don't know of any others who have raised awareness on public land issues nearly as much as BHA. Unfortunately in these days of Tribalism, all the good is tied to the bad by people too tied to their politcal Tribe to think objectively.
RMEF does great work but they have been silent on issues degrading the quality of public land hunting in MT and elsewhere.