New Delhi, Nov. 1 -- Brazil has an unfortunate habit of disappointing. Despite the country's exceptional natural-resource endowment, its growth trajectory resembles what Brazilians call the flight of a chicken (voo de galinha): a brief flutter followed by an inevitable fall back down to Earth. President Luiz Inacio Lula da Silva's surprise re-election raises the risk of another letdown.

By the time he leaves office in 2030, Lula will have occupied the presidency for 16 (non-consecutive) years. Today, Brazil's public finances are already precarious, following nearly four years of loose fiscal policy. Public-sector debt has risen from 73.8% of gross domestic product (GDP) in 2023 to a projected 86.6% by the end of 2026.

Stabilizing debt a...