On the day Mike Pence and Donald Trump both spoke in Washington, a former member of their administration poured scorn on Pence’s attempt to portray himself as a potential Republican presidential nominee, and competitor to Trump, in 2024.

Speaking on CNN, Miles Taylor said: “If you want to know what the Mike Pence vice-presidency was like, Mike Pence is a guy with an erect posture and flaccid conscience. He stood up tall but he did not stand up to Donald Trump.”

Taylor was chief of staff at the Department of Homeland Security when he wrote a famous column for the New York Times under the name “Anonymous”. He then wrote a book, A Warning, expanding on his insider’s account of Trump White House dysfunction.

Reviewing the book in the Guardian, world affairs editor Julian Borger said: “It fails to answer the question that hangs over almost every page: why heed the counsel, however urgent, of someone who is not prepared to reveal who they are?”

Having identified himself as a conservative opponent of Trump, Taylor is now attached to think tanks including Business for America and Renew America Movement.

In Washington on Tuesday, Pence spoke to the Young America Foundation before Trump spoke at the America First Policy Institute. Pence also announced a memoir, So Help Me God, to be published in November.

He said the book would deal with the “severing” of his relationship with Trump over Trump’s demand that Pence refuse to certify electoral college results in key states in Trump’s 2020 defeat by Joe Biden.

Told by advisers he had no such authority, Pence did not do so. Trump supporters attacked the Capitol, some egged on by a tweet in which Trump said his vice-president “didn’t have the courage to do what should have been done”. Some rioters chanted: “Hang Mike Pence.” A gallows was erected outside.

In public hearings about Trump’s election subversion and the insurrection, the House January 6 committee has portrayed Pence’s decision to defy Trump as a brave and noble action. It has also aired testimony suggesting Trump approved of the call for Pence to be hanged.

But as the Republican 2024 field begins to take shape, with Trump suggesting he will soon announce a run, perhaps to head off criminal charges, Pence must appeal to a party largely still in Trump’s thrall.

In Washington on Tuesday, he said: “Some people may choose to focus on the past. But elections are about the future. And I believe conservatives must focus on the future to win back America. We can’t afford to take our eyes off the road in front of us.”

He also said: “I truly believe elections are about the future. That is absolutely essential … that we don’t give way to the temptation to look back.”

On CNN, Taylor said Pence “stood up tall in that speech but he still – after people trying to assassinate him – could not stand up to Donald Trump …

“That tells you everything you need to know about Mike Pence.”