The former Trump cabinet member Nikki Haley was accused of ageism, as well as a startling lack of awareness about senior figures in her own party, after questioning Joe Biden’s mental health and suggesting there should be “some sort of cognitive test” for office holders “above a certain age”.

Haley made the remarks in an interview with the Christian Broadcasting Network – a conservative outlet founded by and often featuring the televangelist Pat Robertson, who turned 91 last March.

Asked about the mental health of the president, who turns 79 later this month, the former ambassador to the United Nations first avoided directly commenting on Biden.

“What I’ll tell you,” she said, “is rather than making this about a person, we seriously need to have a conversation that if you’re going to have anyone above a certain age in a position of power, whether it’s the House, whether it’s the Senate, whether it’s vice-president, whether it’s president, you should have some sort of cognitive test.”

Haley, 49, is widely seen to have ambitions to run for the Republican presidential nomination in 2024. But in a party dominated by older men, her remarks may not have done her too many favours.

The former president Donald Trump is 75 – and has boasted, while in office and facing questions about his mental acuity, of passing a simple cognitive test. The Senate minority leader, Mitch McConnell, is 79. The oldest Republican in the Senate, Chuck Grassley of Iowa, is 88 and has said he will run for another six-year term.

Democratic leadership is also dominated by older politicians. The House speaker, Nancy Pelosi, is 81. The House majority leader, Steny Hoyer, is 82. In the Senate, Dianne Feinstein of California is three months older than Grassley. Chuck Schumer, the majority leader, is a relatively sprightly 70.

Haley pressed on.

“Just like you have to show your tax returns,” she said, “you should have some sort of health screening so that people have faith in what you’re doing.”

Candidates for president do not have to show their tax returns. Trump memorably upended the convention that they did so by refusing to release his.

“Right now,” Haley continued, “let’s face it, we’ve gotten a lot of people in leadership positions that are old. And that’s not being disrespectful. That’s a fact. And when it comes to that, this shouldn’t be partisan. We should seriously be looking at the ages of the people that are running our country, and understand if that’s what we want.”

Finally, Haley came round to the subject of the question.

“You look at Biden,” she said, “and I think there’s a concern. I think there’s a concern when people say, ‘You know, who’s really making the decisions here.’ That’s his job to prove that he’s making the decisions, but it’s not helping us when he says, ‘Oh, I didn’t know that France wasn’t included in the idea that we were going to do this [defence] deal with the UK and Australia.’

“He can’t act like he doesn’t know something. Because every time he acts like he doesn’t know something, from ‘OK, they tell me to call on these reporters,’ you know, he keeps giving signals that he’s not with it.

“So it’s not people hating on Biden, it’s Biden really showing the country that he’s not totally in charge and that makes everyone nervous.”

Amid widespread criticism, Sarah Longwell, publisher of the Bulwark, a conservative anti-Trump outlet, said: “What I’m hearing is: Nikki Haley calls on Donald Trump to release his tax returns and prove mental competency ahead of 2024.”

In South Carolina, where Haley was governor before she joined Trump’s cabinet, a columnist for the State newspaper said her comments “reeked of ageism and that’s nothing to joke about”.

Trudi Gilfillian added: “According to the Equal Employment Opportunity Commission, ‘An employment policy or practice that applies to everyone, regardless of age, can be illegal if it has a negative impact on applicants or employees age 40 or older and is not based on a reasonable factor other than age.’

“Given that standard, perhaps all politicians of all ages should be taking these cognitive tests Haley supports. I’d wager some of the youngest ones likely wouldn’t fare too well.”