Argentina's Oct. 26 midterms will determine whether the government can advance its pro-market reforms or face a sharp decline in governability and investor confidence. A weak result for the government is likely to trigger a significant devaluation of the peso, renewed capital controls and heightened political instability. Argentina will hold legislative elections on Oct. 26 to pick 127 out of the 257 seats in the Chamber of Deputies and 24 of the 72 seats in the Senate. The vote comes two years after libertarian President Javier Milei was elected and at a time when his administration faces significant challenges to pass legislation because of its minority position in the Argentine Congress. The government and its allies in Congress have also struggled to prevent the opposition from passing legislation and overturning a series of presidential vetoes in recent months that restricted funds for provinces, education, healthcare and disaster relief. The pushback...