The biggest threat to Hillary Clinton's presidential aspirations might be the Democratic nominee herself.

That was essentially how Jonathan Allen, co-author of HRC: State Secrets and the Rebirth of Hillary Clinton described the former first lady, New York senator and secretary of state during an extended conversation with Examining Politics, the Washington Examiner's weekly podcast.

The race between Clinton and Republican Donald Trump has tightened this week, following the Democrat's health scare and spate of bad press over scandals related to her use of a private email server during her tenure at the State Department.

"There's a conflict at the heart of Hillary Clinton, which is ... an essential conflict that's important to understand," Allen said. "She wants to be president of the United States and have this role in public life that she's had for the last quarter of a century on the national stage and beyond that in Arkansas.

"And, at the same time, [she] is this intensely private person who has a streak for secrecy or a penchant for secrecy and privacy that kind of borders on paranoia."

Clinton held a solid lead over Trump for most of the summer, a period during which the New York businessman suffered from his own self-inflicted political wounds.

But that led has dissipated since Labor Day as voters have digested coverage of Clinton scandals that have in fact obscured fresh reporting on Trump's own potential scandals, such as his charitable foundation's illegal donation to a Florida politician.

Clinton's problems were probably compounded by her absence from the campaign trail for most of this week, after she nearly collapsed in public on Sunday and was ordered to rest at home to recover from pneumonia. Clinton was scheduled to return to the trail on Thursday.