Launching its state election campaign on Sunday, the Australian Education Union has called for free preschool education for three and four-year-olds.

“Over 50 per cent of three-year-olds in Victoria are missing out on a preschool education," Victorian branch president Meredith Peace said in a statement on Sunday.

"Research shows that children who attend two years of preschool with a qualified preschool teacher have better cognitive, emotional and social development."

The union also wants at least 70 per cent of public tertiary funding directed to TAFE rather than private providers and an average of 1600 new teachers employed each year for the next decade to keep up with population growth.

Victorian Premier Daniel Andrews did not make any commitment on Sunday, but backed his government's education agenda.

"We've put more teachers on, we have provided the biggest boost to special needs education the state has ever seen, TAFE is free under this government, repaired and now on the way to being better than it's ever been," Andrews told reporters.

"And there's been massive investments in the early years because we know that in the education state, in fact in any state, if you don't invest in the smallest Victorians then you limit the life opportunities that they have later on."