Hillary Clinton revealed she considered telling Donald Trump to "back up, you creep" in an infamous election television debate.
The Democratic Presidential nominee is giving her first detailed account of her failed race to become the first female US president in a her memoir What Happened.
Mrs Clinton said she had "let down" her supporters and admitted that she had a long list of regrets in extracts read out on MSNBC's Morning Joe show on Wednesday
But she also accused her rival Donald Trump of playing dirty, accusing him of trying to physically "intimidate" her by repeatedly "looming" behind her during their second television debate.
Mrs Clinton points out that the debate came just two days after Mr Trump's "grab them by the p***y" comments about sexually assaulting women had come to light.
In the book, she recalls considering turning around to to say: "Back up, you creep. I know you love to intimidate women but you can’t intimidate me, so back up."
Looking back, she admitted wondering whether she should have chosen to address his actions.
"It certainly would have been better TV," she said.
"Maybe I have over-learned the lesson of staying calm, biting my tongue, digging my fingernails into a clenched fist, smiling all the while, determined to present a composed face to the world."
Mrs Clinton also admitted that she was still consumed by her failure to beat Mr Trump to the presidency.
"I couldn't get the job done. And I’ll have to live with that for the rest of my life," she writes.
However she said that her memoir would not be a blow-by-blow memoir of the 2016 election as she had "too little distance" to write a dispassionate account.
Instead, it will be her view of an experience that she described as "exhilarating, joyful, humbling, infuriating and just plain baffling".
What Happened is published by Simon & Schuster and will be released next month.