Until 2006, every time the tide rose in the Brazilian shanty town of Brasilia Teimosa, it brought destruction. Poor families forced to live in wooden shacks on stilts overlooking the waterfront lived in fear that the water might take everything they owned, including their homes.

In his first domestic trip as president in 2003 Luiz Inácio Lula da Silva stood on a makeshift stage in the slum and promised things would change.

Within three years, the waterfront had been transformed into a promenade attracting tourists from around the state. Ever since, Brasilia Teimosa has been considered a bastion of support for Mr da Silva and his centre-Left Workers’ Party (PT).

But when the country goes to the…