The only unknown about this ad was exactly when it was going to hit the airwaves.

In her newest TV ad, Georgia Democratic Senate nominee Michelle Nunn hits Republican opponent David Perdue hard over his  remark in a deposition that he "spent most" of his career on outsourcing.

Georgia Senate candidate Michelle Nunn (D) slams her Republican opponent David Perdue for admitting to outsourcing in a 2005 deposition. (Michelle Nunn via YouTube)

"That's right, under oath, David Perdue admitted he spent most of his career outsourcing jobs overseas," says the narrator of the commercial, which was shared with The Washington Post Tuesday.

Politico reported last week that during a 2005 deposition, Perdue, a businessman, was asked to describe his experience with outsourcing and responded, "Yeah, I spent most of my career doing that." His campaign manager said that by "outsourcing," Perdue was referring to a “company contracting with an outside source, not the direct shift of jobs overseas.”

What could make the Nunn ad especially potent is that it relies on Perdue's direct quotes from the deposition. And just in case anyone has doubts about the context, it includes an image of the official transcript.

Georgia is one of about a dozen races that could influence which party controls the Senate next year. Perdue has opened up a small lead over Nunn, recent polls show. But Democratic strategists are hopeful that his outsourcing comment will allow Nunn to make up ground with four weeks left until the election.

Perdue has not backed down from his comment. He told reporters Monday that he was "proud" of his past. "This is a part of American business, part of any business. Outsourcing is the procurement of products and services to help your business run. People do that all day," he said.

In response to Nunn's ad, Perdue spokeswoman Megan Whittemore said in an e-mail, "David Perdue spent his entire career creating and saving American jobs. He grew companies like Dollar General where he created 20,000 new jobs and opportunities for American workers. David has spent 40 years dealing with bad government policies that put our manufacturers at a disadvantage and devastated entire industries."

Updated at 11:10 a.m.