Protesters unhappy about proposed budget cuts march at the State Capitol building on Wednesday in Madison, Wisconsin. (CNN) -- This week's growing controversy about funding public education in Wisconsin is hardly an isolated incident, as 40 states are coping with budget shortfalls totaling $140 billion, which will threaten America's 14,000 school districts for the next five years, one analyst said Thursday. Concerns about funding kindergarten through 12th-grade systems were evident this week in Denver when big education's stakeholders -- the nation's two largest teachers unions, a superintendents group, a school boards group and federal education officials -- met to discuss...