The phrase "partisan issue" refers to a topic or problem that divides people along political party lines. It means that people from different political parties have opposing viewpoints or positions on that particular matter. Full definition
«Our issues are not partisan issues. (towleroad.com)
In the United States particularly, climate issues often become partisan issues, but politicians everywhere must deal with the policy choices that come with battling global warming... (insideclimatenews.org)
These are really non partisan issues and affect everyone in District 19. (greenedems.org)