BBC is reporting that The Brazilian presidential candidate Eduardo Campos, 49, has died in a plane crash, party members and local officials say.
The plane carrying Mr Campos came down in bad weather in a residential area of the port city of Santos, in Sao Paulo state.
Local reports say four other passengers and the two pilots were also killed.
President Dilma Rousseff has declared three days of national mourning and cancelled campaign events.
"The whole of Brazil is in mourning," Ms Rousseff said in a statement.
"We lost a great Brazilian today, Eduardo Campos. We lost a great comrade," she added, calling her rival a "great political leader".
More Details Later