SOUTH BEND, Ind. – Struggling Indiana public school districts are buying billboard space, airing radio ads and even sending principals door-to-door in an unusual marketing campaign aimed at persuading parents not to move their children to private schools as the nation's largest voucher program doubles in size.

The promotional efforts are an attempt to prevent the kind of student exodus that administrators have long feared might result from allowing students to attend private school using public money. If a large number of families abandon local districts, millions of dollars could be drained from the state's public education system.

"If we don't tell people the great things that are happening in our schools, no one else will, especially not now," said Renee Albright, a teacher in Fort Wayne. "There are private enterprises that stand to benefit if they can portray us as failed schools."