The Trump administration on Tuesday said it was revoking the visa of Brazil's ambassador amid an escalating diplomatic fight over alleged U.S. interference ahead of the country's presidential election in October.

The action is meant as a reciprocal measure, a senior State Department official said, after Brazil delayed the formal approval of President Trump's pick to be U.S. ambassador and denied visas to several U.S. officials.

Danny Perez, a Florida politician and Trump ally who was nominated for the job in June, has been unable to take up his post as Brazil's government has withheld the formal approval, known as agrément, required for an ambassador to serve. Brazilian officials had signaled that they could delay approval until after the October elections, leaving the U.S. without an ambassador in Brasília for months, U.S. officials said.

The U.S. isn't expelling Brazil's ambassador, the State Department official said. Instead, the unusual move would leave Ambassador Maria Luiza Ribeiro Viotti residing in the country without a valid visa, which the U.S. will restore if Brazil approves Perez, the official said. It wasn't immediately clear what practical effect the revocation -- which generally bars a visa holder from entering or re-entering the U.S. -- would have on the ambassador, who is already in Washington.

The U.S. wants to have a "normal, productive, transparent" relationship with Brazil, but "reciprocity is the name of the game," the official said.

Brazil's foreign ministry and its embassy in Washington declined to comment.

The State Department said Brazil has denied visas to a delegation that planned to travel to a critical-minerals facility in March, as well as a senior U.S. human-rights official visiting for a routine trip.

The dispute comes as ties between Washington and Brasília have deteriorated. President Luiz Inácio Lula da Silva has accused Washington of interfering in the country's coming elections in October, while the Trump administration argues that the Brazilian authorities have unfairly targeted conservatives and have restricted free speech.

Tensions appeared to ease when the two leaders met privately at the White House in May. But relations have been strained for most of Trump's second term as the U.S. has castigated da Silva's government with 50% tariffs and sanctions over allegations of a political witch hunt against the country's conservatives -- including former President Jair Bolsonaro.

His eldest son, Flávio Bolsonaro, is running against da Silva in the election this fall. Members of da Silva's Workers' Party have expressed concerns that Trump could use the issue of organized crime as a political weapon to aid Bolsonaro in the election. The Trump administration recently designated two of Brazil's largest criminal groups, Primeiro Comando da Capital and Comando Vermelho, as foreign terrorist organizations.