In portions of an interview with
"Oh yeah," he said. "I have to pay our bills."
The interview, which was conducted in Kenya during his tour of Clinton Foundation projects on the continent, was the first the former president has conducted since his wife launched her second bid for the White House.
Last month, a conservative author's new book asserted possible links between major donations to the foundation and favorable actions the U.S. government took on behalf of donors while Hillary Rodham Clinton served as secretary of State.
Peter Schweizer, the author of the book "Clinton Cash," has conceded in interviews that he has no proof of a quid pro quo, but has evidence of suspicious circumstances.
"There has been a very deliberate attempt to take the foundation down," Bill Clinton said. "There's almost no new fact that's known now that wasn't known when she ran for president the first time."
Clinton said he has never done "anything that was against the interests of the United States" through his foundation or in accepting speaking fees. "I asked Hillary about this and she said, 'No one's ever tried to influence me by helping you," he added.
"No one has even suggested they have a shred of evidence to that effect," he said.
While the state of the evidence remains under debate, there's little question that the allegations have damaged Hillary Clinton's standing with the public – although not with the portion likely to take part in Democratic primaries.
A new Wall St. Journal/NBC News poll finds that the share of Americans with a negative view of the former secretary of State rose 6 percentage points over the last month. Americans are now evenly divided over Clinton, with 42% having a favorable view of her and 42% negative.
Among fellow Democrats, however, 76% said they viewed Clinton favorably, a number that has not shifted significantly and which far outpaces the loyalty that any of her potential Republican rivals receive from their party's supporters.
Reflecting the intensity of dislike for Clinton among conservatives, the poll found that one-third of Americans say they have a "very negative" opinion of her. On the other side, 23% said they were "somewhat positive," while only 19% said they were "very positive."
By 51%-32%, voters gave Clinton strong ratings on "being knowledgeable and experienced enough to handle the presidency." But only 25% rated her strongly on "being honest and straightforward," while 50% gave her poor marks on that.
Bill Clinton also contended with low ratings for honesty and straightforwardness during his eight years in office. He has been a strong backer of his wife, but sometimes with mixed results. In the 2008 campaign, Clinton campaigned relentlessly on her behalf, securing votes for her in sometimes far-flung corners of primary states but also occasionally distracting from her message with controversial comments.
The new interview illustrated again that for all Clinton's political pluses, his efforts to dismiss negative stories often add fuel to the fire.
Clinton volunteered to NBC that it was "amusing" to hear questions about whether his wife could relate to middle-class concerns because of the wealth they've accumulated since leaving the White House. He took what appeared to be a jab at Republican hopeful Jeb Bush, saying: "It's OK if you inherit your money, apparently."
"I'm grateful for our success. But let me remind you: When we moved into the White House, we had the lowest net worth of any family since Harry Truman," Clinton said.
Clinton said taking speaking fees was actually a way to avoid conflicts of interest that could arise from other sources of income, and that he turns down many speaking requests if he thought they might raise problems.
"It's the most independence I can get," he said. "If I had a business relationship with somebody they would have a target on their back from the day they did business with me until the end. Any kind of disclosure is a target. But it looks bad. There's no facts, of course, but it looks bad."