Who are the '47 percent'?

Half don't earn enough to pay federal income taxes; many pay other ways.

Do those breaks have support?

Support for the EITC often splits along party lines, with Democrats pushing for a bigger such refundable tax credit, and Republicans pushing to curb or even eliminate it. But as Keith Hennessey, director of the National Economic Council under President George W. Bush, points out, it is the child tax credit that has driven the increase in the numbers of non-income-tax-payers in recent years, as the value of the credit on a per-child basis has risen rapidly under presidents of both parties.

"Most of the increase since the mid-1990s in the number of people who owe no income taxes is the result of the child tax credit," Mr. Hennessey writes on his personal blog. "This policy was created by Congressional Republicans and expanded with Republicans in the lead."

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