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Mississippi Gov. Haley Barbour on Sunday defended fellow Gov. Bob McDonnell for his decision to declare April "Confederate History Month" in Virginia without initially acknowledging the legacy of slavery, saying the controversy "doesn't amount to diddly."

The Virginia governor took heat for his declaration from a slew of top officials, including President Obama and former Virginia Gov. L. Douglas Wilder -- the first black elected governor and a grandson of slaves.

Under pressure, McDonnell on Wednesday apologized, acknowledging a "major omission" and adding in a paragraph condemning slavery. That helped ease the tension over the matter, but Barbour said Sunday that McDonnell did not do anything wrong in the first place.

"I don't know what you would say about slavery, but anybody that thinks that you have to explain to people that slavery is a bad thing, I think that goes without saying," he told CNN's "State of the Union."

"To me, it's a sort of feeling that it's a nit, that it is not significant, that it's ... trying to make a big deal out of something doesn't amount to diddly," he said.

Barbour, a Republican, said his state for years has marked a Confederate Memorial Day, under the leadership of Democratic and Republican governors -- and a Democratic legislature.

"I'm unaware of them being criticized for it or them having their supporters feel uncomfortable with it," Barbour said Sunday.

McDonnell initially defended his decision not to mention slavery in the document, saying there were other aspects to the conflict and he wanted to focus on those "most significant" to his state.

He was the first Virginia governor to make such a declaration since Republican Jim Gilmore in 2001.

In his clarification, McDonnell said the "abomination of slavery" led to the Civil War.