The ad highlights criticism of Romney's economic plan in the Wall Street Journal and Forbes, two influential publications in conservative circles.
"Romney’s economic plan? Timid. Parts of it virtually identical to Obama’s failed policy. Timid won’t create jobs and timid certainly won’t defeat Barack Obama," the narrator says.
"We're going to have a great time with Romney in New Hampshire," Gingrich said in an interview Wednesday with Bloomberg. "He'll win, probably, but it will be much more interesting than he wants."
"Each race generates a wave of national media," Gingrich added. "My goal is to have this become a race between a Massachusetts moderate and a Georgia conservative."
Gingrich had previously pledged to run a positive campaign, hoping that voters would punish his opponents for going negative in their advertisements. But after the tough loss, Gingrich is shifting strategy — although he denies that he is adopting the strategies of his opponents, saying Wednesday it was not negative campaigning "to accurately describe someone's record."
For his part, Romney has said that he expects the critical ads to continue.
"It's a long road. I expect people to come after me," he said in an interview on MSNBC. "And if I do well here, I'll have a target painted on me, and so I expect other folks to come after me. ... And, you know, if I can't stand up to that, I shouldn't be the nominee."
The Gingrich campaign told the New York Times that the ad would begin airing Thursday in New Hampshire and South Carolina, but did not reveal how much they planned to spend.