Washington (CNN) Democratic presidential candidate Julián Castro questioned Vermont independent Bernie Sanders' skepticism for reparations, comparing the scope of monetary compensation for slavery to big-ticket social programs Sanders has called for.

Castro, speaking Sunday on CNN's "State of the Union" with Jake Tapper, said the US should address its "original sin of slavery" and pledged if elected president to "appoint a commission or task force to determine the best way to do that."

Sanders was asked about the issue during a CNN presidential town hall last month and said he supported tackling poverty, inequality and "institutional racism in this country." But pressed on reparations specifically, Sanders said, "What do they mean, I'm not sure that anyone is very clear."

On Sunday, Castro contrasted his own openness to the possibility of paying reparations to the descendants of slaves to a recent ABC interview where Sanders said there were better ways to address the issue than "just writing out a check."

"To my mind that may or may not be the best way to address it," Castro said. "However, it's interesting to me that when it comes to Medicare for all, health care, you know, the response there has been we need to write a big check, that when it comes to tuition-free or debt-free college, the answer has been we need to write a big check."

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