Crouching to sit on a classroom floor, Gov. Mark Dayton mingled with 4-year-olds Friday as he made a pitch for a hefty state spending increase for universal access to preschool in Minnesota.

"You look like you're 65," observed one little boy. "Close. I'm 68," said Dayton, who interacted with kids for about 20 minutes as they sat in a group and later worked on iPads.

Dayton wants lawmakers to approve $348 million in new state spending so that every public school in the state could provide such classes. It's the biggest single general fund spending increase Dayton has proposed this year, and comprises about a fifth of the state's projected $1.9 billion budget surplus.

The group of about 15 children in the prekindergarten class at Newport Elementary School were well-behaved for the governor and his unusually large entourage, including aides and security, area state legislators, school district officials and reporters. Their teachers later said the good showing by the kids was a testament to the benefits of early learning.

"We notice a huge difference between students who do pre-K and those who don't," said Brittany Vasecka, a prekindergarten teacher at the school. The classes are half-day and run five days a week.

In all, 80 percent of students in the South Washington County district attend prekindergarten classes, district officials said. Under Dayton's proposal, both districts that already provide prekindergarten classes and those that don't would both be recipients of the money.

"I don't think we should penalize the school districts that have made this commitment," Dayton said.

But some education advocacy groups have jumped on that lack of a distinction. On Thursday, a business-backed nonprofit called Parent Aware for School Readiness released an analysis contending that about 70,000 low-income kids up to age 3 could have access to early learning scholarships if about $150 million less were to be spent on the universal preschool initiative.

In a news release, the group said that districts with high numbers of "wealthier families whose children are already likely to be ready for kindergarten" don't need the funding Dayton's proposal would provide.

"That ought to be focused on younger children from low-income families," said Ericca Maas, executive director of the group.

If Dayton and lawmakers were to make preschool access universal to 4-year-olds, Maas said, "then next year all of us advocates will be back here saying, 'What about the 3-year-olds?' "

Dayton said he'd be open to more funding for even earlier learning programs. But he said diverting some money away from universal preschool access would run the risk of "pitting 4-year-olds against 3- and 2-year-olds."

The DFL governor's preschool initiative is of a similar character to one of his most-touted successes of his first term, when he and the DFL-led Legislature approved funding for universal all-day kindergarten. Dayton mentioned it frequently during his successful re-election campaign last year.

This year, Dayton must navigate the proposal through a GOP-led House, which has different priorities for both the budget surplus and in state management of schools. House Speaker Kurt Daudt, R-Crown, and other Republicans, while calling universal preschool a worthy goal, have also suggested that some means testing might be needed.