About a year ago, Brazil’s far-right President Jair Bolsonaro had bold plans to conquer the Northeast. The country’s poorest region had proved immune to the president’s charms, being the only part of the country where Mr. Bolsonaro did not win a majority of votes in the 2018 election. It is also where his rejection rates are the highest, by some distance. Even so, at one point it seemed possible that the government could muster the momentum to take over what has traditionally been an electoral stronghold for the center-left Workers’ Party.
Mr. Bolsonaro was empowered by rising approval...