The NRA endorsed Harry for the primary. Also, Reid ran ads all over Nevada quoting LaPierre abotu the range in Vegas using comments like “Harry Reid is a strong gun rights supporter..”
This is not a single issue argument. As I posted above, 10s of millions of new leftist voters would threaten the 2nd amendment as well a the rest of what is left of the power of the real constitution. Some GOP members may be on the wrong side too.