The New York Times reports: Benjamin Franklin did it. Henry Ford did it. And American life is built on the faith that others can do it, too: rise from humble origins to economic heights. “Movin’ on up,” George Jefferson-style, is not only a sitcom song but a civil religion.

But many researchers have reached a conclusion that turns conventional wisdom on its head: Americans enjoy less economic mobility than their peers in Canada and much of Western Europe. The mobility gap has been widely discussed in academic circles, but a sour season of mass unemployment and street protests has moved the discussion toward center stage.

Former Senator Rick Santorum of Pennsylvania, a Republican candidate for president, warned this fall that movement “up into the middle income is actually greater, the mobility in Europe, than it is in America.” National Review, a conservative thought leader, wrote that “most Western European and English-speaking nations have higher rates of mobility.” Even Representative Paul D. Ryan, a Wisconsin Republican who argues that overall mobility remains high, recently wrote that “mobility from the very bottom up” is “where the United States lags behind.”

Liberal commentators have long emphasized class, but the attention on the right is largely new.

“It’s becoming conventional wisdom that the U.S. does not have as much mobility as most other advanced countries,” said Isabel V. Sawhill, an economist at the Brookings Institution. “I don’t think you’ll find too many people who will argue with that.”

One reason for the mobility gap may be the depth of American poverty, which leaves poor children starting especially far behind. Another may be the unusually large premiums that American employers pay for college degrees. Since children generally follow their parents’ educational trajectory, that premium increases the importance of family background and stymies people with less schooling.