John Sununu, a top surrogate for Mitt Romney's presidential campaign, on Thursday night suggested that former Secretary of State Colin Powell endorsed President Barack Obama because he is black.

"I'm not sure how important that is," Sununu replied when asked about the endorsement by CNN host Piers Morgan. "I do like the fact that Colin Powell's boss, George Herbert Walker Bush, has endorsed Mitt Romney all along."

"And frankly, when you take a look at Colin Powell, you have to wonder if that's an endorsement based on issues, or whether he's got a slightly different reason for preferring President Obama."

"What reason would that be?" Morgan asked.

"Well, I think when you have somebody of your own race that you're proud of being President of the United States, I applaud Colin for standing with him," Sununu said.

Powell, a Republican, endorsed Obama for the second time on Thursday, saying he was concerned by Romney's economic and foreign policy.

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