With most of his colleagues unable to choke out a syllable of opprobrium for Donald Trump, Republican senator Mitt Romney has stood out as a willing, if reserved, critic of the president.

Romney has called Trump’s international efforts to gin up bad news about Joe Biden “wrong and appalling”, and earlier this month he took the Senate floor to call the US abandonment of Kurds in northern Syria “a bloodstain in the annals of American history”.

Now, in double interviews published at the weekend, Romney signaled he might go one step further, possibly leading a breakaway group of Republican senators to turn on Trump in the event that the president is impeached.

For Trump to be removed from office following potential impeachment in the House of Representatives, which is controlled by Democrats, the US Senate, which is controlled by Republicans, would have to hold a trial and vote Trump out. About 20 Republican senators would need to turn on Trump to make it happen – long-shot math no matter what Romney says or does.

But the former financier who saw his national political dreams dashed in a 2012 presidential loss to Barack Obama might now see another opportunity to make a mark.

In a profile for the Atlantic, reporter McKay Coppins, who has closely followed Romney’s career since before the 2012 election, writes: “Here, in the twilight of his career, he seems to sense – in a way that eludes many of his colleagues – that he’ll be remembered for what he does in this combustible moment.”

“I do think people will view this as an inflection point in American history,” Romney told Coppins.

In a separate interview with Axios, Romney repeated his criticism of Trump for asking China and Ukraine to “investigate” Biden, a potential 2020 rival for Trump though the former vice-president has been sinking in the polls.

“It was shocking, in my opinion, for the president to do so – and a mistake for him to do,” Romney told Axios. “I can’t imagine coming to a different point of view.

“We certainly can’t have presidents asking foreign countries to provide something of political value. That is, after all, against the law.”

In both interviews, Romney, a leader in the Mormon church, also described his disapproval of Trump’s character. “He has elements, I’m sure, of honor in his life,” Romney told Axios. “And there’s things that I think are not honorable.”

Romney has even been keeping a clandestine Twitter account, using the handle “Pierre Delecto”, to keep up on politics news and, very occasionally, to offer mild rebuttals to negative news about himself or to censure the president, the Atlantic and Slate revealed.

Romney is floating his criticism of Trump at a time when the president is politically vulnerable, with a low approval rating nationally and the impeachment inquiry steaming ahead.

But Romney has not always advertised the courage of his convictions when it comes to Trump.

Mitt Romney has an awkward dinner with Donald Trump to discuss the secretary of state job in November 2016 in New York. Photograph: Drew Angerer/Getty Images

As a candidate in 2012, Romney sought Trump’s endorsement, which he obtained in a suitably choreographed press conference at a Trump property in Las Vegas. After Trump’s election, Romney had dinner with his supposed nemesis to see about the secretary of state job, for which Trump later ridiculed him.

“Mitt Romney never knew how to win,” Trump tweeted earlier this month. “He is a pompous ‘ass’ who has been fighting me from the beginning, except when he begged me for my endorsement for his Senate run (I gave it to him), and when he begged me to be Secretary of State (I didn’t give it to him). He is so bad for R’s!”

Does Romney know how to win? He’s studying up on the question, Coppins reports.

“Romney is taking the prospect of a Senate trial seriously – he’s reviewing The Federalist Papers, brushing up on parliamentary procedure, and staying open to the idea that the president may need to be evicted from the Oval Office,” Coppins wrote.

“The gentleman from Utah suddenly appears ready to unload.”