The United States has long touted its record of sending disadvantaged children to college. That pride is misplaced, a study now finds.

The odds that a young person in the U.S. will go to college if their parents haven't — 29 percent — are among the lowest of developed countries, according to a report released Tuesday by the Paris-based Organization for Economic Cooperation & Development.

The results indicated the challenge of one of President Obama's economic and educational goals: increasing college attainment in the U.S. relative to other countries. The U.S. ranks 14th among 37 countries in the percentage of 25- to 34-year-olds with higher education. A generation ago, the U.S. ranked among the top in the world.

"The odds that a young person will be in higher education if his or her family has a low level of education are particularly small in the U.S.," the report said.

Declining economic mobility in the U.S. has been the subject of social science research that challenges a mainstay of the American dream, that of children achieving more that their parents. The issue, particularly for the middle class, lies at the heart of this year's presidential campaign between Obama and Republican challenger Mitt Romney.

In the study, the U.S. ranked below all countries except Canada and New Zealand in sending the children of less educated parents to four-year colleges.

The evidence suggests a culprit: inequity among elementary and high school students, such as the concentration of immigrants and other disadvantaged citizens in lower-quality schools, according to Andreas Schleicher, the international organization's deputy director for education.

Rising college tuition doesn't seem to account for the difference, though U.S. student-loan levels could, Schleicher said in a briefing with reporters. Higher education debt has reached $1 trillion, raising alarm among families.

The U.S. still has a leg up in higher education because of its older population. In the U.S., 42 percent of 25- to 64-year- olds have a college degree, a percentage lagging only Canada, Israel, Japan and Russia.

With other countries making gains and less advantaged families left behind, the U.S. faces a risk that could damage its international competitiveness, Schleicher said.

In the U.S., "there are real challenges in terms of social and economic mobility," he said.