Hillary Clinton's campaign team have questioned the timing of the Federal Bureau of Investigation's probe into her personal email use.
FBI head, James Comey, is under pressure to reveal what the bureau knows and explain what Mrs Clinton has allegedly done wrong.
US Senator Harry Reid has suggested that FBI Director James Comey "may have broken the law" by disclosing the fact that new action is being taken in the Clinton email probe so close to the election.
The senate Democratic leader also accused Comey of having a "double standard" and being selective in the information that was being publicised, according to Reuters.
It comes as law enforcement officials confirmed to NBC News on Sunday that the FBI had obtained a warrant to search emails related to Clinton private server investigation that were discovered on ex-congressman Anthony Weiner's laptop.
The emails were found on a laptop seized from Clinton's aide's estranged husband, ex-congressman Anthony Weiner.
The FBI Director's letter has placed a dark cloud of suspicion over Mrs Clinton, and no one - perhaps not even he himself - knows why.
The presidential candidate has called for the FBI to fully explain the new emails that have come to light.