Former chancellor George Osborne has claimed democracy and capitalism are "in crisis", as he announced the launch of a new book.
Mr Osborne dubs the current state of politics the "Age of Unreason", the provisional title of the book, with "populist nationalism and prejudice on the rise".
He also points specifically to controversial US presidential candidate Donald Trump, with Mr Osborne suggesting Mr Trump poses a risk to "peace, prosperity and security".
The key ally of former prime minister David Cameron has now returned to the Tory backbenches, after six years as chancellor.
Announcing the book, Mr Osborne called for the forces of free markets and open society to take back control of the political debate.
Mr Osborne said: "My book is about the future. I want to apply the lessons I've learnt in victory and defeat to the urgent challenge of this Age of Unreason.
"Capitalism and democracy is in crisis. The West is in retreat. The forces of populist nationalism and prejudice are on the rise, amplified by new technology.
"The likes of Donald Trump say to people, what the hell have you got to lose. The answer is, a lot. Peace, prosperity and security.
"It's time to say so. It's time for the defenders of open societies and free markets to fight back."
He will take a year to write the book. Mr Osborne has recently launched a new think tank to promote the Northern Powerhouse, one of his key policies as chancellor.
Arabella Pike, publishing director of William Collins, said the book "could not be more timely or important".