Who are the "Forty-seven percent of Americans" who Republican presidential candidate Mitt Romney says pay no income tax?

Mitt Romney interviewed by Univision's Jorge Ramos and Maria Elena Salinas (Joe Raedle/Getty Images)

A study by the nonpartisan Tax Policy Center says 46 percent of U.S. households paid no federal income tax last year.

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Some got senior citizens tax breaks, some are low-income and some got tax breaks for college tuition.

The study says among all who don't owe, 9 out of 10 make $50,000 or less. But 4,000 households earning more than $1 million a year didn't pay federal income tax last year.

Romney says committed to all Americans

Mitt Romney is further explaining himself after a videotape surfaced in which he told wealthy donors that his job isn't to worry about the 47 percent of Americans who don't earn enough to pay taxes.

Romney said on the Spanish-language TV network Univision Wednesday that his campaign "is about the 100 percent in America." Romney says "this is a campaign about helping people who need help."