As Hillary Clinton returns to the campaign trail after spending most of the past two weeks fundraising, questions linger about her emails and ties to the Clinton Foundation when she was secretary of state, giving her rival Donald Trump ammunition to attack.
The businessman’s offensive has narrowed Mrs Clinton’s lead in the polls.
The state department said on Tuesday that as many as 30 previously unknown emails may contain details about the deadly 2012 attack on the US outpost in Benghazi, Libya, that killed four Americans. The incident and Mrs Clinton's handling of the response have spawned the most vicious Republican attacks against the Democrat.
Government lawyers told a US federal judge that the emails were not included in the 55,000 pages of emails previously provided by Mrs Clinton’s lawyers in a tranche handed over to the state department. This arose in response to the controversy over her use of a personal email server to conduct government business as secretary of state.
The FBI, which investigated her use of the private email address but decided not to recommend criminal charges, handed over about 14,900 emails purportedly not among those disclosed by Mrs Clinton.
The Democratic nominee has said that she handed over any emails concerning government business and deleted emails that were of a personal nature. The tranches of emails now being released stem from a legal action taken by the conservative group, Judicial Watch, which is pushing for their disclosure before the November 8th election.
Mr Trump has accused Mrs Clinton of operating a “pay-to-play” scheme through the Clinton Foundation by offering access to wealthy foreign donors to her family’s charity when she was working at the state department, a charge she has vehemently denied.
The Republican nominee's criticism has been bolstered by calls from the editorial boards of liberal newspapers such as New York Times and the Boston Globe for Mrs Clinton to cut her ties with the Clinton Foundation and to close the charity should she be elected president because of potential conflicts of interest.
The Clintons plan to restrict foreign and corporate donations should she be elected.
Mr Trump has also rounded on Mrs Clinton for not holding a press conference in 270 days when the Republican has held at least 14 news conferences this year.
Online political forecaster, FiveThirtyEight, now gives Mrs Clinton a 77 per cent chance of being elected to the Oval Office, down from 89 per cent a fortnight ago.
The latest NBC News/Survey Monkey weekly tracking poll on Tuesday showed Mrs Clinton’s advantage narrowing by two points to 48 per cent to 42 per cent.
"He is having a marginal effect, but I don't think it is having enough effect to change the dynamic of the race very much," said Democratic strategist Brad Bannon.
“In a normal presidential election, the emails especially would have crippled Hillary Clinton’s campaign but this is not a normal election. This is not a referendum on Hillary Clinton. This is much more a referendum on Donald Trump’s fitness to hold office.”
Mrs Clinton spoke to the American Legion convention in Ohio on Wednesday a day after raising several million dollars at three fundraising events in the exclusive Hamptons resort in New York on Tuesday.
This included an estimated $3.7 million, according to CNN, at an event where Paul McCartney, Jimmy Buffett and Jon Bon Jovi performed for donors.
