Newt Gingrich frequently mentions another man's name in the same breath with President Barack Obama: Saul Alinsky.

In his South Carolina primary victory speech last month, for example, the former Georgia congressman said he draws his understanding of America from its Founding Fathers while Obama draws his “from Saul Alinsky, radical left-wingers and people who don’t like the classical America.”

You could be forgiven for not being familiar with Alinsky. He’s not commonly well-known, though Secretary of State Hilary Clinton wrote her senior thesis at Wellesley College about his methods.

The son of Russian Jewish immigrants, Alinsky grew up in Chicago and sought to improve conditions for the poor and powerless. He taught them unorthodox and provocative ways to organize and protest. Alinsky, who died in 1972 when Obama was 10, wrote “Rules for Radicals,” a guide for how people could come together and bring about social change. In that book he urged his readers to “to maneuver and bait the establishment so that it will publicly attack him as a ‘dangerous enemy.’ ”

Gingrich is aware how Alinsky’s name resonates with conservatives who believe the president modeled himself after him, said Alinsky’s biographer, Sanford Horwitt. Obama, a fellow community organizer from Chicago, was inspired by Alinsky and worked around people who were trained by Alinsky’s associates, Horwitt said.

Gingrich often presents voters with a choice during his campaign speeches: him or Obama-Alinsky. “This is how big the difference is,” the former House speaker told supporters Tuesday in Columbus, Ohio. “Barack Obama believes in the radicalism of Saul Alinsky and in the centralized bureaucratic system of Europe. I believe in the Declaration of Independence, the Federalist Papers and the Constitution.”

Diane Cole of Winchester, Ohio, was among those who showed up to see Gingrich speak in Columbus this week. She said she bought Alinksy’s “Rules for Radicals” after reading excerpts online. She is worried the country is drifting away from the Constitution and toward Alinsky -- a trend she said that began with Teddy Roosevelt's presidency.

“I’m worried about it for my kids,” she said. “I don’t want them growing up in the Soviet Union.”

But Alinsky never embraced socialism, said Horwitt, the author of “Let Them Call Me Rebel. Saul Alinsky: His Life and Legacy.” Alinsky was a “pragmatic populist” who once sought to help the Catholic bishop of Milan combat communist unions in Italy, Horwitt said.

“He was just thoroughly in love with what America stood for,” Horwitt said. “He realized that in a lot of places in the world there wouldn’t be a Saul Alinsky. He would be shot or hanged for doing a lot of these things.”

Meanwhile, a segment of the very people Gingrich has been targeting for support in his campaign -- tea party activists -- has embraced Alinsky’s tactics. FreedomWorks -- a Washington-based organization that recruits and trains tea party activists -- hands out copies of “Rules for Radicals” to its trainees.

Gingrich, himself, has been accused of acting like Alinsky. For example, conservatives have criticized Gingrich for attacking Mitt Romney’s tenure as head of a private equity fund that pushed some companies into bankruptcy and put some people out of work.

“What the hell are you doing, Newt?” former New York Mayor Rudy Giuliani said last month on Fox News. “I expect this from Saul Alinsky, Newt.”

Alinsky’s son, David, rejects Gingrich’s criticism of his father. But he sees a potential silver lining in that Gingrich is bringing more attention to his father’s work.

“The more these guys spew their vitriol,” he said, “the more people are going to turn around and say, ‘Hey, maybe there is something to this guy.’ ”