WASHINGTON - Michael Cohen, U.S. President Donald Trump's former personal lawyer and fixer, on Thursday promised to show how Trump cheated in the 2016 election with Russian help in an upcoming book titled "Disloyal, A Memoir." "Trump had cheated in the election, with Russian connivance, as you will discover in these pages, because doing anything — and I mean anything — to 'win' has always been his business model and way of life," Cohen writes in the book's foreword, which was published online on Thursday. The 3,700-word foreword does not reveal anything new about Russia's interference in the 2016 presidential election, and it was not clear if the book would. Former Special Counsel Robert Mueller last year concluded that Russia waged a major campaign to help Trump to victory in 2016. Mueller did not find evidence of a criminal conspiracy between Trump's campaign and Russia, but he did detail extensive contacts between the campaign and Russian operatives. Cohen worked closely with Trump for years before turning against him, most publicly in testimony to Congress last year prior to Trump's impeachment. Cohen said he knows where Trump's metaphorical "skeletons" are buried because he buried them. White House spokesman Brian Morgenstern responded by attacking Cohen's credibility. "He readily admits to lying routinely but expects people to believe him now so that he can make money from book sales. It’s unfortunate that the media is exploiting this sad and desperate man to attack President Trump,” Morgenstern said. Trump has called Cohen "a rat," and a liar, and Cohen said he faced repeated death threats from Trump supporters. Cohen, 53, is serving a three-year sentence for tax evasion, false statements and campaign finance violations, the last related to payments to silence women who alleged affairs with Trump before the 2016 presidential election. Cohen was released to home confinement in May given the risks of catching COVID-19 in prison, but then was briefly imprisoned again last month. A federal judge last month ruled Cohen had been subjected to retaliation for planning to publish his book, and ordered him released again. A lawyer for Cohen declined to comment.