Longtime Clinton ally Lanny Davis is due to release a book in October that excoriates former FBI Director James Comey for his role in the 2016 election.

Davis' work aims to trace Hillary Clinton's email controversy and the timeline from Comey's July 2016 congressional testimony in which he declared the end of an investigation into her emails to his bombshell announcement just before the November election that the investigation had been reopened.

"In 'The Unmaking of the President 2016,' attorney Lanny J. Davis shows how Comey's misguided announcement — just eleven days before the election — swung a significant number of voters toward Trump, winning him an Electoral College victory — and the presidency," the book's publisher, Simon and Schuster, said.

Davis argues that state-by-state polling data shows that had the election been held on Oct. 27, Hillary Clinton would not only have won the popular vote but also the Electoral College by a substantial margin.

He further contends that despite Trump's behavior, Russian interference, and reports of Clinton's gaining traction in states like Georgia, Arizona, and even Texas, it was Comey's Oct. 28 letter about the Clinton investigation that completely reshaped the landscape of the election in favor of Trump.

"Davis proves with raw, indisputable data how Comey's October surprise changed American history in the blink of an eye and cost Hillary Clinton the presidency," Simon and Schuster said.

The book is scheduled to be released Oct. 24.