Co-chair of Romney campaign has tried to distance himself from statement that Colin Powell endorsed Obama because of race

The fallout from a claim by a prominent Romney supporter that former Bush secretary of state Colin Powell endorsed Barack Obama on racial grounds showed no sign of abating on Friday.

John Sununu, who is the co-chair of Mitt Romney's campaign, said on Thursday that Powell endorsed the president because both men are black.

He told CNN: "When you take a look at Colin Powell, you have to wonder whether that's an endorsement based on issues or whether he's got a slightly different reason for preferring President Obama".

Sununu, a former governor of New Hampshire, added: "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 later issued a statement attempting to distance himself from the remarks, but Democratic mayor of Newark, Cory Booker, said Sununu's comments were "disrespectful" in an interview on CNN.

"Whatever he meant or not, it was a statement that is unfortunate and just reflects a lack of understanding and sensitivity," Booker said. "He's gotten himself in a jam, and he's going to wear that jam for a while."

Booker said Sununu's claims were "unfortunate, and we should talk about those issues and presumptions that still often exist" but added that in "these last days, let's focus on the candidates themselves, what their plans and platforms are".

The row comes as the Romney campaign is still under pressure to distance itself from Richard Mourdock, the Senate candidate who is personally endorsed by Mitt Romney but has been the subject of intense criticism after claiming that pregnancies from rape are "something that God intended to happen".

In his statement on Thursday, Sununu did not apologise for his remarks, although he appeared to row back somewhat.

"Colin Powell is a friend and I respect the endorsement decision he made and I do not doubt that it was based on anything but his support of the president's policies. Piers Morgan's question was whether Colin Powell should leave the party, and I don't think he should," Sununu said.

Colin Powell endorsed Obama in 2008 and announced his support for a second term on Thursday, praising the president's handling of the economy.

"I think, generally, we've come out of the dive and we're starting to gain altitude," Powell told CBS This Morning, adding that "housing is now starting to pick up" and "consumer confidence is rising".

The former secretary of state also criticised Romney's malleable positions on foreign policy. "The governor who was speaking on Monday night at the debate was saying things that were quite different from what he said earlier," Powell said. "I'm not quite sure which Governor Romney we would be getting with respect to foreign policy."

It is not the first time Sununu has been criticised for comments about Obama. After the first presidential debate in Denver, Sununu described Obama as "lazy" on MSNBC, leaving host Andrea Mitchell visibly shocked.

"What people saw last night, I think, was a president who revealed his incompetence – how lazy and detached he is and how he has absolutely no idea how serious the economy problems of the country are and how he has failed to even address them," Sununu said.

In July he told Fox News that Obama has "no idea how the American system functions".

Sununu added: "And we shouldn't be surprised about that, because he spent his early years in Hawaii smoking something, spent the next set of years in Indonesia, another set of years in Indonesia, and frankly, when he came to the US, he worked as a community organizer, which is a socialized structure."