He parleyed his way to Brazil’s presidency with a vote-winning barrage of scaremongering and bombast.

But eight months into Jair Bolsonaro’s far-right tenure, there is growing discomfort over the president’s inability – or refusal – to mind his mouth, and the impact this is having on Brazil’s place in the world.

“The president has become a risk for the country,” the broadsheet O Globo pronounced this week in an editorial lamenting how Bolsonaro’s “verbal incontinence” was costing Brazil international friends.

Brazil’s president has long been notorious for his hateful and homophobic declarations – he once proclaimed that he would prefer a dead son to a gay one. But even by Bolsonaro’s loquacious standards, recent weeks have been notable.

Jair Bolsonaro. Photograph: Marcos Correa/AFP/Getty Images

Since the start of August, Bolsonaro has called for criminals to “die on the streets like cockroaches”, described Argentina’s likely incoming leaders as “leftie crooks”, called a Brazilian journalist a “plonker”, lashed out at Norway and mocked Emmanuel Macron and Angela Merkel for challenging him over a surge in Amazon deforestation.

He has also added a “scatological fixation” to his rhetorical repertoire, O Globo pointed out, cracking a succession of jokes about excrement that dumbfounded critics but delighted his fans.

“Poo every other day,” Bolsonaro told a reporter on 9 August when asked if economic development was compatible with environmental protection.

Five days later, he returned to his faecal theme. “We are going to put an end to poo in Brazil,” he told a rally of flag-waving supporters in the north-east of the country, before clarifying that by “poo” he meant corrupt politicians and “communists”.

Other Bolsonarian digressions have made fewer headlines, such as a YouTube interview in which he pondered on the menstruation of “little indigenous girls” and a Facebook Live appearance where he quipped about his justice minister having sex with his environment minister.

Bolsonaro’s backers paint such freewheeling as part of their leader’s ad-libbed political charm. “He’s super sincere,” his son, Eduardo, said before Bolsonaro’s landslide election victory last year. “What he says to his mates, he says to the press … and it’s thanks to this that he’s got where he has.”

Even some of the president’s foes have urged Bolsonaro to keep blathering, if only to reveal his true, unsavoury nature to Brazilian voters and to the world.

“Say more, Mr Sincere,” the Brazilian writer Mariliz Pereira Jorge wrote in the Folha de São Paulo newspaper earlier this month. “Say more, every day, without fail, so it becomes common knowledge, lest we forget for a single day, the autocratic, despicable, heartless, obtuse being who misgoverns this country.”

Thomas Traumann, a Brazilian commentator and former communications minister, said dedicated “Bolsonaristas” revelled in their leader’s garrulousness – which he saw as a deliberate Bolsonaro tactic to energise his base.

He said: “There is a logic to it. He isn’t doing this for no reason … Trump does the same.”

But Traumann said the president’s prattling was an international PR disaster that would carry a diplomatic and economic price. By portraying Brazil as an unreliable, Amazon-destroying bogeyman, Bolsonaro risked isolating the South American country and triggering a costly boycott of Brazilian products. Traumann said: “This isn’t a joke. It is real. These things happen.”

This week both Germany and Norway announced that they were suspending tens of millions of pounds of contributions to an Amazon protection fund because of the Bolsonaro administration’s stance on the environment.

Traumann said: “Why would any country want to deal with a second Trump? You’re obliged to deal with one Trump because it’s the United States. But there’s no reason to deal with a second Trump. Brazil just isn’t that important … We aren’t essential.”

In a recent interview, Roberto Abdenur, Brazil’s former ambassador to Beijing and Washington, predicted that Bolsonaro would be shunned by European leaders as a result of his incendiary words and deeds.

“I’d almost bet money that in the coming years there won’t be a single invitation for Bolsonaro to visit from these countries – not from the Germany of Merkel or her successor; not from Macron’s France, and so on,” Abdenur said.

With Bolsonaro unlikely to pipe down, Brazilian writers have begun pondering ways to survive his four years in power. “I’ve been thinking about banning Bolsonaro from this column,” Ruy Castro mused in the Folha de São Paulo this week. “The paper it’s printed on isn’t thick enough to absorb the muck that comes out of his mouth.”