A post-election meeting at which advisers led by Rudy Giuliani attacked campaign lawyers and urged Donald Trump not to accept his election defeat was “a new low” for a president “well acquainted with rough-and-tumble debates”, Mike Pence writes in a forthcoming memoir.

Of the meeting in November 2020, the former vice-president writes: “In the end, that day the president made the fateful decision to put Giuliani and [attorney] Sidney Powell in charge of the legal strategy … The seeds were being sown for a tragic day in January.”

By openly blaming Trump for events leading to the January 6 insurrection, when a pro-Trump mob attacked the US Capitol in an attempt to overturn Joe Biden’s election victory, Pence risks angering Republicans he must court as he considers the next nomination for president.

His memoir, So Help Me God, will be published on 15 November. Axios published a short excerpt on Monday.

Pence writes: “What began as a briefing that Thursday afternoon quickly turned into a contentious back-and-forth between the campaign lawyers and a growing group of outside attorneys led by Rudy Giuliani and Sidney Powell, an attorney who had represented Gen Mike Flynn [Trump’s first national security adviser, fired for lying to the FBI].

“After the campaign lawyers gave a sober and somewhat pessimistic report on the state of election challenges, the outside cast of characters went on the attack … Giuliani told the president over the speakerphone, ‘Your lawyers are not telling you the truth, Mr President.’

“Even in an office well acquainted with rough-and-tumble debates, it was a new low …. [and] went downhill from there.”

Trump’s culpability for the Capitol attack has been examined and presented by the House January 6 committee and is being investigated by the US justice department.

The former president is in legal jeopardy on other fronts: election subversion, the unauthorized retention of White House papers after the end of his presidency, his business affairs and a defamation lawsuit from a writer who alleges he raped her.

Trump denies wrongdoing and remains dominant in polls for 2024. He is reported to be seeking campaign hires while waiting until after the midterm elections next week to make a formal announcement.

Pence’s presidential ambition is no secret but although the January 6 committee has presented him as a hero for refusing to cooperate with Trump’s election subversion, he has work to do if he is to persuade Republican voters he is the man to take on Biden.

Polling gives Trump huge leads over his nearest challenger, the Florida governor, Ron DeSantis. If Trump is removed from the equation, DeSantis enjoys healthy leads over figures including Pence, the Texas senator Ted Cruz and Donald Trump Jr.