Newt Gingrich greets supporters during a rally Nov. 17 in Jacksonville, Fla. (Stephen Morton/AP)

A confident and at times defiant Newt Gingrich defended himself Friday against growing questions about his lucrative consulting career, and he acknowledged that how he handles the vetting process will determine whether he can be “a legitimate front-runner” for the Republican presidential nomination.

Calling his recent surge toward the top of the polls “almost disorienting,” Gingrich fielded questions at a news conference here about his myriad money-making ventures in the decade since his tenure as House speaker ended. They include consulting contracts with Freddie Mac, the quasi-public mortgage company, and millions of dollars from health-care corporations seeking access to him.

“Somebody who’s a front-runner for the presidency of the United States should get a full vetting,” Gingrich said. “It’s the nature of the process. If I’m able to answer them [questions] in a way that the American people feel comfortable, then I’ll be a legitimate front-runner.”

A few minutes earlier, answering a question from a Harvard Business School student, Gingrich said: “In terms of being both consistent and willing to absorb a pretty substantial beating from the elite media, I’m probably as willing to sacrifice for this country’s future as anybody you’ve seen in public life in your lifetime.”

Gingrich added a new page to his campaign Web site Friday, “Answering the Attacks,” in which he tries to respond to questions about a menu of controversies, including “Personal Life,” “Lobbying” and “Global Warming/Cap and Trade.” The page notes that with Gingrich’s “vast amount of experience . . . comes over 7,000 votes, over 1,500 speeches, thousands of television and radio appearances, thousands of articles and op-eds and 24 books to scrutinize.”

The Washington Post reported Friday that health-care firms and industry groups paid Gingrich’s think tank, the Center for Health Transformation, at least $37 million in dues since 2003 for “direct Newt interaction” and other access. Asked by reporters what those companies received in return, Gingrich said they got to visit with “a really important guy who really knows a lot and who really has lots of information.”

“You had a chance to come and be in meetings with somebody who had been speaker of the House, who understood Washington, who understood history,” Gingrich said. “I’ve been studying health policy since 1964. . . . I think I have genuine standing. I’ve been listed, I think, for four or five years in a row as one of the top people in Modern Health magazine’s rating.”

Earlier this week, Bloomberg News reported that Freddie Mac paid Gingrich up to $1.8 million in consulting fees. Asked about those payments, Gingrich said he urged his consulting firm, Gingrich Group, in which he said he is no longer a partner, to publicly release records of the earnings.

Late Thursday, in an interview with Fox News, Gingrich said he worked only about an hour a month giving advice to Freddie Mac. That would suggest that Gingrich earned up to $30,000 an hour giving Freddie Mac strategic advice.

“I think less than maybe once a month, they would drop by,” Gingrich said. “We’d spend an hour. It would always start with me listening. I’d always say, ‘What are you trying to solve? What are your concerns? What are you trying to get done?’ And I’ve done this with many, many clients.”

The role as an influence broker could become a political problem for Gingrich, reminding voters that he is a longtime Washington insider despite his outsider rhetoric.

Gingrich was in Cambridge on Friday with his wife, Callista, for a screening of one of their documentaries, “A City Upon a Hill,” at Harvard’s Institute of Politics. After the hour-long film, Gingrich took questions from the audience.

On foreign affairs, he said: “I don’t know that I’m a hawk so much as I’m an owl. I think we need wisdom.”

Gingrich talked about what he called his “extraordinarily radical proposals,” including one to put children in poor neighborhoods to work as school janitors.

“Most of these schools ought to get rid of the unionized janitors, have one master janitor and pay local students to take care of the school,” Gingrich said. “The kids would actually do work, they would have cash, they would have pride in the schools, they’d begin the process of rising.”

Gingrich added that most successful people started their first jobs between ages 9 and 14, selling newspapers or washing cars. “They all learned how to make money at a very early age. What do we say to poor kids in poor neighborhoods? ‘Don’t do it.’ Remember all that stuff about ‘Don’t get a hamburger-flipping job?’ The worst possible advice you could give to poor children.”

Gingrich closed his remarks predicting he’d win two presidential terms. “I will need you with me every day for eight years,” he said.

Eggen reported from Washington.