A group that opposes the “strong mayor” initiative says that a citizen is challenging the initiative through a lawsuit. The group SAVE Sacramento announced it will hold a press conference about the lawsuit Tuesday at 10 a.m. at City Hall. Detailed information about the lawsuit was unavailable at press time.  Mayor Kevin Johnson backs the initiative, which would provide him with many new powers. Matt Kelly, executive secretary of the Sacramento-Sierra Building and Construction Trades Council, talked about the lawsuit Monday. Kelly, who is affiliated with SAVE, said the plaintiff is Bill Camp, executive secretary for the Sacramento Central Labor Council. He added that Camp is suing as