ST. PAUL, Minn. (AP) - Gov. Mark Dayton has vetoed an education budget that he says isn't big enough, setting up a special session of the Minnesota Legislature.

Dayton had promised he would block the bill if lawmakers didn't add to the $400 million allocated to public schools. The package included nothing for one of Dayton's top priorities - preschool for 4-year-olds throughout the state.

Legislators adjourned at midnight without changing the package, and the governor delivered the promised veto Tuesday afternoon.

In his veto letter, Dayton said the $400 million wasn't enough given the state's nearly $2 billion surplus. He said the state needs to invest "in our students and young children."