GOP front-runner Herman Cain struggled to defend his 9-9-9 tax plan on NBC's Meet The Press, admitting for the first time that some people with lower incomes would pay more under the plan.

"Some people will pay more," he told David Gregory. "But most people will pay less... The people who spend more on new goods will spend more."

Cain's plan would establish a 9 percent flat tax and sales tax — drawing criticism from Democrats and Republicans alike.

Cain said you can't consider state taxes when evaluating his plan because "these are replacement taxes."

"There are invisible taxes built into everything we buy. The price of goods goes down [under 9-9-9]," he said.

Cain said his tax plan would pass because its simplicity resonates with the American people — and that even those who see their taxes increase will see benefits under the 9-9-9 plan.

On foreign policy, Cain said he is informed by the writings of former UN ambassador John Bolton and former Secretary of State Henry Kissinger — but insisted he was not a neo-conservative. "I'm not familiar with the neo-conservative movement," he admitted.

Cain added that he opposes abortion is all instances — including rape and incest — unless the life of the mother is at risk, in which case "it is up for the family to decide."

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