James Comey clearly hoped his televised interview on Sunday would be a go-signal for other principled Republicans to break away from Donald Trump and denounce him. In the interview, Comey declared Trump to be “morally unfit to be president”, and compared him to a mafia don, someone without a scintilla of decency. He provided evidence to support these harsh words.

The word “decency” has never been more vital than in this toxic political moment. If James Comey’s book means anything, it is an urgent plea for those in power to come to the defense of decency.

At other points in American history, our politics have shifted overnight in defense of decency. One of the most famous moments came in 1954, when the Boston attorney Joseph Welch thundered “Have you no sense of decency?” at the red-baiting demagogue Joseph McCarthy, who had falsely accused one of Welch’s staff lawyers of being a communist.

An amazed, large television audience looked on, similar to the millions who tuned in to watch Comey eviscerate Trump. Virtually overnight, McCarthy’s immense national popularity evaporated. His villainous core had at last been exposed and the country, it turned out, had had enough of him.

Where are the voices of principled Republicans turning against Donald Trump? Have they no decency?

With Comey’s new book and sensational interview, has the country reached a similar tipping point?

Alas, there are few signs that it has. Where are the voices of principled Republicans turning against Donald Trump? Have they no decency?

I’ve talked to enough highly placed former GOP lawmakers and officials to know that many of them privately believe that Trump should be removed from office. But they are afraid to speak out, afraid to alienate the base of their party, afraid, in fact, of the bully himself, Donald Trump, and the legions of rightwing zealots he can deploy on Twitter or at his large rallies.

It’s sad. One former Republican senator told me he couldn’t speak out publicly against Trump because he serves on a non-partisan government commission. Another former Republican cabinet member doesn’t like to speak on the record, period, although in private has muttered that Trump should be impeached.

It’s terribly sad that former First Lady Barbara Bush just died. But the Bush family is known to scorn Trump and it’s past time for the two former Presidents Bush, 41 and 43, to speak publicly about a president who makes a mockery of public service.

Where is Barack Obama? It is custom for the ex-president to refrain from attacking the new one, but observing such normalcy seems not only quaint but obscene given the reality of a president who disrespects the basic rule of law.

Where is John McCain? Yes, he has terrible health problems, too, but he is always the lion in winter and his voice is desperately needed.

‘Some of Trump’s sharpest critics have gone radio silent.’ Photograph: Mike Segar/Reuters

Instead, some of Trump’s sharpest critics have gone radio silent. During the 2016 primaries, Mitt Romney blasted Trump as a “fraud” and called his proposals “worthless” in an unprecedented attack on the GOP frontrunner. Now he needs conservative support in his bid for a US Senate seat in Utah and has positioned himself to the right of Trump on immigration.

Then there is Paul Ryan, who dared to distance himself from Trump when the Access Hollywood tape went public but tried to go along to get along as House speaker. He’s leaving Washington DC with his tail between his legs and, as far as I can tell, keeping his gag rag firmly in place.

Supposedly, more Republican lawmakers may speak out if and when Trump dares to fire Robert Mueller and Rod Rosenstein. Senator Lindsey Graham has said Trump would be signing his own execution papers if he goes through with these firings. Well, what about the behavior and actions that Comey details in his book? The disgraceful loyalty oath he tried to enforce? The chain of lies? The pathetic reaction to disclosures of Russian meddling in the US election as purely a problem of spin?

In his book, Comey writes about risking his career when he counselled John Ashcroft, then George W Bush’s attorney general and lying hospitalized, not to sign the re-authorization of the Bush-Cheney domestic surveillance program secretly launched after the 9/11 terrorist attacks. This was Comey’s finest hour, and it required him to stand up to the vice-president and his warped legal adviser, David Addington.

He knew he had done right, he recalled, when Mueller, his predecessor as FBI director, “came in moments later and he stood and leaned down and spoke to the desperately ill attorney general and told him that, in every man’s life, there comes a time when the good Lord tests him. And then he said, ‘You’ve passed your test tonight.’”

Comey added: “I was overcome with emotion hearing that. And had this sense that the law held. The law held. It felt like a dream to me, that we were in a hospital room with senior officials trying to get the desperately ill attorney general to sign something. But it wasn’t a dream. And the law held,” he said.

That was a moment when decency won in America. We desperately need another.