Washington - Former US President Bill Clinton defended his charitable foundation's acceptance of large foreign donations on Monday, thrusting himself into a controversy that is weighing on the presidential candidacy of his wife, Hillary Clinton."I don't think there's anything sinister in trying to get wealthy people in countries that are seriously involved in development to spend their money wisely in a way that helps poor people and lifts them up," Clinton told NBC News from Kenya, in an interview taped over the weekend.His decision to emerge from the sidelines and speak out about the Clinton Foundation reflects concerns about getting Hillary Clinton's campaign for the 2016 Democratic presidential nomination back on a sound footing after it took a pounding in recent weeks.The former first lady, also a previous secretary of state and former senator from New York, has attempted to present herself as a candidate who would fight for everyday Americans.But her campaign has been on the defensive over questions about foreign donations to the family's charitable organisation and whether her work as President Barack Obama's first-term secretary of state was influenced by the donations."There is no doubt in my mind that we have never done anything knowingly inappropriate in terms of taking money to influence any kind of American government policy," Clinton said. "That just hasn't happened."Hillary Clinton faces only limited opposition in her drive for the nomination, but the drumbeat of criticism has taken a toll on her image.An AP-GfK poll released on Friday showed that among Democrats, only 34% said they were excited by her candidacy, while 36% were merely satisfied. Another 19% said they were neutral, and 9% were disappointed or angry.Scrutiny of the foundation has focused on foreign donations as well as on Bill Clinton.A New York Times review of the organisation two weeks ago found that Clinton had accepted a $500 000 speaking fee from Renaissance Capital, a Russian investment bank with ties to the Kremlin.As has been customary for the Clintons over the years, the former president described the controversy as old news."There's been a very deliberate attempt to take the foundation down. And there's almost no new fact that wasn't known when she ran for president first time," Clinton said, referring to Hillary Clinton's 2008 campaign.Clinton said he would continue making paid speeches while his wife is a candidate, saying: "I gotta pay the bills. And I also give a lot of it to the foundation every year."Still, he said he would consider stepping back from the foundation if she is elected to the White House in 2016.