Social media to echo size of September 7 protests

Vast groups of pro-Bolsonaro demonstrators are expected to take to the streets across Brazil today September 7, in a series of protests defending the far-right president in his war of words with the Supreme Court and Congress. While the major events are scheduled for the capital Brasília and the country’s biggest city São Paulo, the repercussions of marches on social media are likely to be just as important for Mr. Bolsonaro.

The president’s supporters have been gearing up for the September 7 protests — held on Brazil’s Independence Day — ever since Mr. Bolsonaro only managed to draw disappointing crowds for a similar...