Hillary Clinton has dismissed swirling questions about her family foundation as little more than political attacks from Republicans eager to gain an early advantage in the 2016 US presidential contest.

Mrs Clinton, campaigning for the Democratic nomination in the liberal bastion of Keene, New Hampshire, hit back against accusations foreign governments that made donations to the Clintons' charity received preferential treatment from the State Department while she served in Barack Obama's administration.

"We will be subjected to all kinds of distractions and attacks," she said after a round-table event at a wood furniture factory. "I'm ready for that. I know that that comes, unfortunately, with the territory."

She is making her first campaign visit this year to New Hampshire, the first-in-nation primary state beloved by the Clinton family for giving both her faltering 2008 effort and her husband Bill's struggling 1992 presidential campaign a second wind.

She also took issue with economic views expressed by members of her own party, offering a dark assessment of a "stalled out" US recovery, a judgment at odds with President Obama's brighter view of what the nation has achieved on his watch.

Mrs Clinton was asked by reporters about Peter Schweizer's coming book, Clinton Cash: The Untold Story Of How And Why Foreign Governments And Businesses Helped Make Bill and Hillary Rich.

The book claims the Clinton family received speaking fees and donations in return for favours to various foreign interests doled out while she was US secretary of state. Senator Rand Paul, a 2016 Republican candidate, said that would make people "question whether she ought to run for president".