A "staunch defender" is someone who strongly supports or protects something or someone, even in difficult or challenging circumstances. Full definition
The opposing senators almost uniformly count themselves as staunch defenders of national security and the military. (dotearth.blogs.nytimes.com)
Kenney makes both Lougheed and Klein — despite their respective records as staunch defenders of Alberta's interests — look like pussycats. (morinvillenews.com)
TCTA leaders and staff remain staunch defenders of public education, research - validated modifications, and even things like choice within the public school system. (tcta.org)