“Most middle-class parents can’t afford a few hundred bucks a week for private preschool,” Obama told his audience. “And for the poor children who need it the most, the lack of access to a great preschool education can have an impact on their entire lives. And we all pay a price for that.”

The president said that he remembered from his own parenting that finding good child care can be hard, and expensive.

“The size of your paycheck, though, shouldn’t determine your child’s future,” he said. “So let’s fix this. Let’s make sure none of our kids start out the race of life already a step behind.”

States would have to meet certain benchmarks to qualify for federal preschool support under Obama’s plan, which would involve meeting state-level standards, employing qualified teachers and monitoring student learning.The federal government is already in the preschool business with Head Start, a program for low-income families with children from birth to age 5. Some studies have shown that the benefits of Head Start have a “fadeout” period by around third grade.

Kenneth Dodge, director of the Duke University Center for Child and Family Policy, said research studies show that preschool has positive effects as children enter kindergarten and elementary school.

“Then the question is how long the effects last,” he said. “But that depends on the school system they’re entering.”

A conservative policy would give money that otherwise would be spent on Head Start to parents so that they could put their children in private or church-based preschools, said Lindsey Burke, an education fellow at the conservative Heritage Foundation in Washington.

“Head Start has been a 48-year-long failed experiment with government preschool, and I’m afraid we’ll see more of the same, based on the president’s proposals,” Burke said.

She said birth to age 5 was a pivotal learning period, “which is why I wouldn’t want the government involved in such a critical time. We want children with families, with parents.”

Kris Perry, executive director of the First Five Years Fund, an education advocacy group, said the quality care for disadvantaged children from birth to age 3, combined with expanded access to pre-kindergarten, was “exactly what has proven to work in early childhood education programs.”

“We know learning begins early, and it’s good common sense that you can’t start at 5 and expect children to catch up,” said Helen Blank, director of Child Care and Early Education at the National Women’s Law Center. “We’ve taken some steps, but we’ve got a long way to go to close the gap.”