No doubt about it, President Obama wants to spend even more on government preschool programs, including a "significant expansion" of the federal Early Head Start program. He called for it in his State of the Union Address, then traveled to Atlanta two days later to second his own motion.

Specifically, the president wants Early Head Start to enroll a greater number of "infants and toddlers, serving children from birth through age 3." He also wants to expand state preschool programs for 4-year-old children through increased federal spending, while at the same time paving the way for Head Start to become even more expansive.

Under this scenario, state government will educate America's 4-year-olds, while the feds take care of our infants and toddlers. Move over Mom: Washington is here to take care of your child from cradle to adulthood.

The problem, of course, is that Uncle Sam doesn't make a very good Mommy. For example, there is overwhelming evidence that Head Start simply doesn't work. So why expand a program proven to fail the poor children it was designed to serve?

Less than two months ago, the Department of Health and Human Services (HHS) released its long-awaited Head Start Follow-Up Study. This definitive report concluded that the nearly $8 billion program has little to no impact on cognitive, social-emotional, health, or parenting practices of participants. On a few measures, access to Head Start actually had harmful effects on children.

This was a scientifically rigorous evaluation that tracked 5,000 3- and 4-year-old children through third grade. By third grade, HHS found, Head Start had little to no positive effect on participating children. Among those who entered as 3-year-olds, as well as those entering as 4-year-olds, the program produced no statistically measurable effects on cognitive ability, including numerous measures of reading, language and math ability.

And access to health care? No impact there, either. Access to Head Start had no statistically measurable effect on all five health measures, including receipt of dental care, health-insurance coverage and overall child health status.

The federal government has a long record of failure when it comes to implementing effective early-childhood education programs. Early Head Start, created during the 1990s, is a federally funded community-based program that serves low-income families with pregnant women, infants and toddlers up to age 3. It is intended to improve the cognitive, social and emotional development of infants and toddlers from low-income families.

Advocates of the program assert that a rigorous evaluation of the program proved that it did, in fact, "produce meaningful, though modest, positive effects." True enough, if you're interested only in short-term results. At age 3, children participating in Early Head Start did show some gains in cognitive and social-emotional development, compared with a control group not participating in the program. However, the devil is in the details.

The short-term benefits produced by Early Head Start appear to be dependent on race. These initial results arose almost exclusively among black children, not white and Hispanic children. Black children comprised 34 percent of participants, while Hispanic and white participants made up 24 percent and 37 percent, respectively. The program appears to provide only some initial benefits to only a minority of its clientele.

More importantly, a long-term follow-up study released last year found that even these beneficial impacts faded away by the fifth grade (not an uncommon finding for social programs). The sole exception came in the area of social-emotional outcomes. Black program participants did slightly better on measures of reduced aggressive and rule-breaking behaviors.

Overall, however, Early Head Start had no meaningful effect on academic performance. The program is ineffective at improving reading, vocabulary and math skills for anyone who manages to progress beyond elementary school.

Once upon a time, President Obama declared that he was willing to eliminate "government programs shown to be wasteful or ineffective." Further, he asserted that "there will be no sacred cows, and no pet projects. All across America, families are making hard choices, and it's time their government did the same." Unfortunately, he has not lived up to his words.

Federal early childhood education programs have failed - expensively and emphatically. It's time to send these failed sacred cows out to pasture.

-Lindsey M. Burke is the Will Skillman Fellow in education policy and David Muhlhausen is a research fellow in empirical policy analysis at the Heritage Foundation, a conservative think tank and advocacy group.