Add Rudy Giuliani to the list of Republicans who think Newt Gingrich and his super PAC have gone too far with their attacks on Mitt Romney's business record.

The former New York City mayor, who's had nice things to say about Gingrich (particularly in relation to his old rival, Romney) in the past, went on Fox News this morning to call Gingrich's line of attack "ignorant, dumb," and something he'd expect from Saul Alinsky, the late Chicago activist who preached confrontation to ignite political change.

"What the hell are you doing, Newt?" Giuliani said this morning on "Fox and Friends." "The stuff you're saying is one of the reasons we're in this trouble now. This whole ignorant populist view of the economy that was proven to be incorrect with the Soviet Union with Chinese communism."

Gingrich has lambasted Romney in the past few weeks for killing jobs during his tenure as the head of Bain Capital. A pro-Gingrich super PAC is out with a 28-minute documentary this week that accuses Romney of being a "corporate raider" who made big profits for investors while laying off workers.

"I'm shocked at what they are doing," Giuliani said today of Perry and Gingrich. "It's ignorant, dumb, it is building something we should be fighting in America: ignorance of the economic system, playing  on the dumbest most ridiculous ideas about how you grow jobs."

Giuliani added: "What they are doing to Mitt right now is totally, absolutely unfair and bad for the Republican Party."

The anti-Romney documentary will be broken up into shorter segments for a $3.4 million ad-buy that will air both on South Carolina television and nationally during the Rush Limbaugh radio show.

"Was Mitt Romney a job creator, or a corporate raider?  That's the question conservatives are asking," the radio ad's announcer intones darkly. "Like a vulture, he hunted for vulnerable companies.  He took them over, loaded them with debt and collected whopping fees.  He cut costs and cut jobs, and picked at the remains."

Limbaugh similarly blasted Gingrich for the ads, saying they prove his "singing from the same hymnal" as Occupy Wall Street protesters and accusing him of "going Perot" in trying to prevent Romney's election to get back at him for the negative ads he ran against Gingrich in Iowa, a reference to Ross Perot, the Texas billionaire who made a third-party run for the presidency in the 1990s.

"I just think this is very unfortunate," Limbaugh said on his radio show. "This is not the kind of stuff you want said by Republicans."

Rick Perry delved into a Gingrich-style line of attack against Romney's business career Tuesday, saying Romney was involved in "vulture capitalism." By Wednesday morning Perry had removed that line from his stump speech.

Gingrich, on the other hand, said today he will not back off his "crony capitalism" characterization of Romney.

"I'm not going to back down or be afraid to say we the American people have the right to know and any candidate for president has an obligation to tell us," Gingrich said. "I think that these extraordinarily wealthy institutions are going to somehow bring enough pressure to bear to say you better shut up, tells you just how bad-off the system has gotten."

ABC News' Elicia Dover and Steven Portnoy contributed to this report.