DENVER (AP) -- State government attorneys told Colorado Supreme Court justices that legislators should have discretion over school funding in an historic case contending the state's school funding scheme is unconstitutional.

Meanwhile, an attorney for parents and 21 school districts urged the court to step in to protect low-income students falling behind their peers across the state.

The lawsuit argued on Thursday seeks to settle a yearslong debate over how Colorado should fund schools to give all students an opportunity to succeed. The state can have major implications on the already cash-strapped budget.

A ruling is months away.

Nearly half of the state budget goes to schools, and Colorado attorneys say the state can't afford to spend more on education. Plaintiffs say they want the state to spend money where it's needed most.