COLUMBIA, S.C. (AP/WVOC) - South Carolina's charter school law has slipped a few spots in a national advocacy group's annual ranking.

The National Alliance for Public Charter Schools ranks South Carolina's law 15th this year out of 43 states, down from 12th previously.

The report released this month says the drop is due to other states' aggressive changes.

An accountability bill that makes it easier to shut down a failing charter school is up for debate in the state Senate. The House passed it unanimously last year.

Charter schools are public schools that must meet all state and federal accountability laws but have greater flexibility.

More than 22,000 students attend a charter school in South Carolina.