Ronald Reagan famously called it the 11th commandment: “Thou shall not speak ill of any fellow Republican.” But, for the Jewish conservatives who were at the heart of the “Never Trump” movement – those Republicans who vowed not to support their party’s candidate in last November’s election – it was a commandment they could not keep.

Two months after Donald Trump took the oath of office, few are showing signs of second thoughts.

Perhaps the most high-profile and vociferous of the Republican Jewish rebels last year was Bill Kristol, the son of Irving Kristol, the so-called “Godfather of neoconservatism”. After serving as then vice president Dan Quayle’s chief of staff, Mr Kristol went on to found and edit The Weekly Standard, America’s leading conservative magazine. The driving-force behind the bid to persuade a third-party conservative to enter the race against Mr Trump and Hillary Clinton, Mr Kristol was famously labelled a “renegade Jew” by Breitbart News, the website formerly run by Steve Bannon, the president’s chief strategist.

Barely 48 hours after Mr Trump’s inauguration, Mr Kristol tweeted simply: “Je ne regrette rien.” That may be his gentlest comment thus far on the 45th president. With the exception of the nomination of Neil Gorsuch to the Supreme Court, Mr Kristol suggested one month into Mr Trump’s tenure at the White House, “it’s worse than I expected”. His dislike of the president reflects the tenor of the criticisms levelled by other Jewish conservatives over the past year. During the election campaign, it was Mr Trump’s populism and his seeming disrespect for the constitution and the rule of law, rather than worries about his electability, which was at the heart of their concerns.

In office, they feel the president’s language and actions have vindicated their stance. “Trump is a demagogue [and] demagogues are dangerous,” Mr Kristol warned soon after the inauguration. The president’s attack last month on the media as the “enemy of the people” exemplified the problem. It was not, Mr Kristol argued, “something one expects in normal US or liberal democratic discourse”.

David Frum, a fellow conservative who worked as a speechwriter for George W Bush, shares similar fears. His cover story in this month’s Atlantic magazine paints a grimly realistic picture of how America could follow the example set by Hungary, which has slowly slid down the path to autocracy since the election of Viktor Orban in 2010. “We are living through the most dangerous challenge to the free government of the US that anyone alive has encountered,” Mr Frum writes. “What happens in the next four years will depend heavily on whether Trump is right or wrong about how little Americans care about their democracy.”

Another Bush administration alumni, Eliot Cohen, vociferously opposed Mr Trump during the election but nonetheless initially argued that young conservatives should cautiously serve in the new administration if asked to do so. However, he swiftly changed his mind, appalled by the appointment of Mr Bannon and the “excusing and normalising [of] this sinister character” by other conservatives. Mr Cohen believes his fears have been more than borne out by Mr Trump’s first weeks in office. “I’ve been in this town for 26 years. I have never seen anything like this. I genuinely do not think this is a mentally healthy president,” he said in an interview last month.

Max Boot, a leading conservative foreign policy expert who endorsed Mrs Clinton, is keen that the focus on the far-right ideologue Mr Bannon not detract from the president’s own culpability. “It’s just about impossible to imagine … Trump acting in a more presidential manner, because he’s been the same obnoxious bully for the past 70 years,” Mr Boot wrote of the administration’s chaotic start.

Amid the myriad examples of that chaos, one is illustrative. Elliot Abrams, a veteran of the Reagan and Bush administrations, had been widely tipped to become Rex Tillerson’s deputy at the State Department. Despite his previous well-documented opposition to Mr Trump, his Oval Office interview with the president for the post passed off well. He was, though, subsequently rejected when Trump was made aware – reportedly by Mr Bannon – of Mr Abrams’ past criticisms. For Mr Trump, in victory there is no hint of magnanimity.