He also told the health care companies that paid him he would increase "your channels of input to decision makers” and grant “access to top transformational leadership across industry and government.”

But Gingrich staff said that the former Speaker only promoted ideas and policies that he believed in, and wrote into his contracts that he would "not provide lobbying services of any kind."

Gingrich himself denied having every lobbied Tuesday in South Carolina, arguing that he didn't need the money.

“I did no lobbying of any kind, period,” Gingrich said. “For a practical reason — and I’m going to be really direct, OK? I was charging $60,000 a speech and the number of speeches was going up, not down.”

Previously, Gingrich has maintained that he simply offered strategic advice to clients, including mortgage giant Freddie Mac.

"I was being paid to offer a series of — and I did this, as I said a while ago, at a number of companies who would come in and ask for advice on a wide range of things. And as long as they were topics that I was interested in and topics that I cared about, I was very happy to share ideas with people," Gingrich said.

"What I didn't do and would not do is I didn't go and lobby the Congress. I didn't go and lobby the executive branch. I didn't try to represent any position I didn't believe in beforehand. And I think that's a very big difference between being a lobbyist and being a strategic consultant,” he said.

So far, questions about the extent to which Gingrich did or did not lobby Congress seem to have had little effect on his campaign, with the former Speaker leading most Republican national polls.

And while Americans are skeptical of Gingrich's claims that he did no lobbying - 37 percent believe that he did, according to a Reuters Poll released last week - almost half - 46 percent - of the Republicans surveyed said the lobbying story had no impact on their view of the candidate. Only 31 percent said that the revelations left them with a less favorable view on Gingrich.