Hillary Clinton has fronted up to her stunning loss to Donald Trump in the 2016 US election in a new memoir.
CNN News purchased an advance copy of the book, titled What Happened, and has reported on some of its contents before its official release next week.
Mr Trump's victory was a major upset and one of the most shocking results in political history.
Ms Clinton was the frontrunner in almost every major poll, with the odds of her winning the presidency standing at 90 percent on the day of the election.
But despite Ms Clinton receiving almost 2.9 million more votes, Mr Trump won the electoral college and was declared President Elect.
Ms Clinton all but disappeared from the public eye in the wake of her loss, but is now ready to open up on why she lost to a reality TV star.
She writes that she misjudged the political atmosphere of the election, and underestimated the skill of her opponent.
"I think it's fair to say that I didn't realize how quickly the ground was shifting under all our feet. I was running a traditional presidential campaign with carefully thought-out policies and painstakingly built coalitions, while Trump was running a reality TV show that expertly and relentlessly stoked Americans' anger and resentment."
Ms Clinton takes ownership of the result, saying she as the candidate must accept responsibility.
"I go back over my own shortcomings and the mistakes we made. I take responsibility for all of them. You can blame the data, blame the message, blame anything you want but I was the candidate. It was my campaign. Those were my decisions."
However Ms Clinton has some choice words for Bernie Sanders, her rival for the Democratic nomination who ignited a wave of political engagement across the country through his progressive policies.
"He didn't get into the race to make sure a Democrat won the White House, he got in to disrupt the Democratic party," she writes.
"Every time I wanted to hit back against Bernie's attacks, I was told to restrain myself. My team kept reminding me that we didn't want to alienate Bernie's supporters. President Obama urged me to grit my teeth and lay off Bernie as much as I could. I felt like I was in a straitjacket.
"Nonetheless, his attacks caused lasting damage, making it harder to unify progressives in the general election and paving the way for Trump's 'Crooked Hillary' campaign."
Ms Clinton also criticises former Vice President Joe Biden for his post-election comments.
"Joe Biden said the Democratic party in 2016 "did not talk about what it always stood for and that was how to maintain a burgeoning middle class,'" Ms Clinton writes.
"I find this fairly remarkable, considering that Joe himself campaigned for me all over the midwest and talked plenty about the middle class."
She says sexism played a part in her inability to connect with voters.
"What makes me such a lightning rod for fury? I'm really asking. I'm at a loss. I think it's partly because I'm a woman".
Ms Clinton describes her 2.30am phone call in which she conceded the presidency to Trump as "one of the strangest moments" of her life.
"I congratulated Trump and offered to do anything I could to make sure the transition was smooth," she writes.
"It was all perfectly nice and weirdly ordinary, like calling a neighbor to say you can't make it to his barbecue. It was mercifully brief. I was numb. It was all so shocking."
What Happened will be released on September 12.