INDIANAPOLIS -- Indiana school superintendents and board members were warned on Friday by their own lobbyists that if they don't act to move back the start of school, the Legislature will do it for them.

Frank Bush, executive director of the Indiana School Boards Association, and John Ellis, executive director of the Indiana Association of Public School Superintendents, said in a letter that action is needed to prevent what they termed "an onerous mandate" from the General Assembly.

They said schools should at least move the start of school back to late August, or the Legislature may go further next year and mandate a post-Labor Day start.

"The explanation for early-August has generally been to prepare students for September ISTEP testing, but the test is now administered in the spring, which seemingly voids testing as a reason," the letter reads. "Naturally, there are other reasons to start earlier than Labor Day, such as ending first semester before the December holidays, but it will be difficult to defend in the legislature early-August absent a fall ISTEP."

A bill mandating a later school calendar passed the Senate, but died in the House.

Sponsors have tried to revive the measure, but with limited success.