From President Obama’s recent budget announcement proposing a $68.6 billion hike in the federal tobacco tax to help pay for universal pre-K, to New York City Mayor Bill de Blasio (D), Virginia Gov. Terry McAuliffe (D), and governors and legislators nationwide, there is a clamor for universal pre-K.

Republicans have been more reluctant, but some, including Oklahoma Gov. Mary Fallin and Michigan Gov. Rick Snyder, have joined the chorus.

Polls underscore this emerging consensus—84 percent of Democrats and 60 percent of Republicans tell pollsters they support the idea.

But resources are scarce and the rush to legislate is ill-informed.  Headlines captured Obama’s State of the Union support for federal investment but overlooked an important sentence in his address: “Research shows that one of the best investments we can make in a child’s life is high-quality early education.” The last four words are key.

The debate concentrates on increasing access but fails to distinguish between effective early learning, which drives school readiness, and childcare, which does not.  Not all ‘pre-K’ is high quality and many childcare programs lack early learning.  The need for systemic change that prepares all young children for school success lies at the periphery of the debate, instead of the forefront.

This lack of clarity is damaging because it is the absence of effective early education for disadvantaged children that perpetuates the so-called “word gap” separating them from their more advantaged peers.

Academic research, tracking families from every socio-economic group, found that children born into low-income families heard, by age three, roughly 30 million fewer words than those from more affluent backgrounds.  Recent Stanford University analysis found an intellectual processing gap that appears as early as 18 months as a consequence. 

Underserved students also begin school with much less well-developed background knowledge, numeracy, comprehension and behavioral skills than those acquired by classmates with parents of greater means.

The word gap, and skill behavior differences, drive what is known as the achievement gap.  Because disadvantaged students arrive at kindergarten millions of words behind their peers and lack early learning skills, they perform much less well at school, with negative effects that last a lifetime.

Ending the achievement gap in preschool can break the endless cycle of “school turnarounds,” student dropouts, wasted lives and lost potential that frequently comes at a high social cost.  Erasing the achievement gap before kindergarten would get K through 12 education out of the business of what Secretary Duncan calls “playing catch-up.”

Sadly, current political dialogue only scratches the surface in terms of real solutions.

Much discussion revolves around Head Start, a Great Society anti-child poverty program that has radically improved nutrition and social services for economically disadvantaged children.  However, Head Start is not designed to provide a robust language, vocabulary, and early literacy component to prepare more children for school readiness. 

Discussion of Head Start has been captured by opponents keen to cut its funding and supporters who want to spend more.  Both sides miss the point: are scarce taxpayer resources invested effectively? Improving Head Start by replicating the way public charter schools have been authorized is one path forward.  This means considering time-limited performance contracts awarded with grants for planning and education program development, and with operators held accountable for results. 

Add to this confused debate advocates' overstating the effect of forty-year-old longitudinal studies.  The Perry Preschool study in Michigan, conducted in the 1960s, and the North Carolina Abecedarian Project, observed during the 1970s, demonstrated significant long-term benefits.  But enthusiasts argue that the effects of these evidence-based programs are common to all early childhood programs.  That isn't realistic.

By contrast, recent multi-year statewide research conducted from 2005 to 2012 by the National Institute for Early Education in New Jersey revealed strong gains from a state Supreme Court-mandated early education program.

The study concluded that, over two years, New Jersey’s initiative closed about half of the achievement gap between low-income children and their more privileged counterparts before kindergarten.  Evidence-based programs such as Every Child Ready have been similarly effective. 

Quality early learning should be defined in terms of important measurable outcomes that lead to success in school.  Such proven programs need to be brought to scale.

The achievement gap deprives us all of skills that disadvantaged students never develop.  How many doctors, engineers and scientists, among other valuable professionals, does society lose?

Public education could be the great equalizer it is supposed to be by closing the achievement gap before kindergarten.  Intelligently investing in genuinely effective early education is the way forward.

McCarthy is president and CEO of the Appletree Institute for Education Innovation.