As Brazil’s Supreme Court decides the legal fate of Jair Bolsonaro, the former president accused of plotting a coup, the nation is bracing for greater backlash from a powerful supporter of the right-wing populist: President Trump.

Brazil’s top court began weighing the case this week against Mr. Bolsonaro, who is accused of overseeing a vast plot to cling onto power after losing the 2022 election. Faced with a trove of prosecutorial evidence, analysts say that Mr. Bolsonaro is likely to be convicted in a trial expected to finish next week.

Brazilian authorities are now bracing for what they believe is a realistic possibility: further sanctions by Mr. Trump targeting members of Brazil’s highest court or the nation’s financial institutions, according to two Brazilian government officials who spoke anonymously to discuss a sensitive issue.

Mr. Trump has called the charges against Mr. Bolsonaro, a political ally, a “witch hunt” and has been trying to bully Brazil into dropping them, imposing tariffs of 50 percent on the nation and targeting the Supreme Court justice overseeing the case with some of the harshest sanctions the United States can apply.

As a result, Brazil is preparing for punitive measures to be expanded in response to Mr. Bolsonaro’s prosecution, the government officials said. In anticipation of such an outcome, Brazil’s attorney general last week hired a Washington-based law firm to “defend” the country against American sanctions and represent its interest in the United States.

The law firm, Arnold & Porter Kaye Scholer, did not immediately respond to a request for comment.

In an interview on Friday, Brazil’s finance minister, Fernando Haddad, downplayed the risk of further U.S. sanctions. He said the government’s focus was on protecting Brazil from the measures Mr. Trump had already imposed, which he called an “unjustifiable aggression” on the nation’s sovereignty.