DENVER – Former New York mayor Rudy Giuliani Wednesday said Barack Obama’s choice for vice president, Sen. Joe Biden, is "a big mistake.”

"I think it was a very big mistake to pass up Hillary Clinton, who had 18 million Democrat votes and Joe Biden had 9,000. I think Barack Obama is suffering that backlash here at the Democratic convention,” he said in a morning satellite interview.

VIDEO: Giuliani extended interview

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He also recalled that Biden and Clinton, during the primary process, called Obama "unprepared to be president.”

Giuliani made an unsuccessful run in the GOP presidential primary.

Meantime, at the Democratic Convention Wednesday, a military wife from Chesapeake will speak about her support for Sen. Obama.

Beth Robinson’s husband is a Marine and has several tours in Iraq.

She was part of a roundtable with Michelle Obama on August 6 at Old Dominion University in Norfolk.