When he decided to run for president, Gingrich “disentangled himself from most of the firms,” she writes. But some of his business dealings continue to raise eyebrows in Washington, she says, including up to $1.8 million Gingrich received as a consulting fee from the mortgage giant Freddie Mac. Gingrich said he was acting as a “historian” for Freddie Mac — not a lobbyist.

“He argues that what he did was give them advice,” she tells Fresh Air’s Terry Gross. “He also says he warned them that their business model was flawed. There is no secondary source that has been willing to confirm that. But the fact is, he was hired to help them promote their agenda. So I think this has become a big problem for him out on the campaign trail. And his opponents are going to say, ‘How are we supposed to press the arguments about Fannie and Freddie in next fall’s election if our standard-bearer was on their payroll?’ “