The coronavirus pandemic has so far proven to be a boost for many autocratic leaders around the world, who have managed to exploit the crisis to expand and tighten their hold on power. But the situation is different for at least one far-right demagogue, for whom the pandemic is shaping up to become the key line in his political obituary: Brazil’s Jair Bolsonaro.

The political future of a president who has been called the “Trump of the Tropics” now hangs in the balance as Bolsonaro continues to actively exhort Brazilians to reject public health measures, even as the number of COVID-19 cases in the country climbs rapidly. In recent days, Bolsonaro has lost two of the most popular members of his Cabinet in circumstances that left him politically wounded. Now, the Supreme Court is looking into allegations—from Bolsonaro’s own justice minister—that the president meddled with the police and obstructed justice, a move that could ultimately sink his presidency. ...