Brazilian President Luiz Inácio Lula da Silva said Thursday that his government has not been successful in trying to negotiate the 50% tariff on Brazilian imports that U.S. President Donald Trump has threatened to impose.

Brazil’s President forcefully rebuked Trump after the U.S. leader called the prosecution of Lula’s predecessor, Bolsonaro, a “witch hunt” and hiked tariffs on the Latin American nation.

Brazil is scrambling to avert punishing 50% U.S. tariffs in a week's time, but high level talks are stalled and U.S. companies are reluctant to confront U.S. President Donald Trump over the issue, officials and industry leaders say.