Declaration comes amid fears Jair Bolsonaro could attempt January 6-style coup to retain power if voted out in October

Brazilian democracy faces a moment of “immense danger”, a manifesto signed by almost a million citizens has warned amid growing fears president Jair Bolsonaro could refuse to accept defeat in October’s election.

The declaration – whose backers include major figures in business, politics, science and the arts – comes after Bolsonaro escalated his attacks on Brazil’s voting system and summoned hardcore supporters to hit the streets “for the last time” before the 2 October vote.

Moves to question integrity of voting system come amid poor polling for far-right leader facing October election

Electoral officials and senior politicians have criticised the Brazilian president, Jair Bolsonaro, after the far-right leader called foreign diplomats to the presidential palace and made unfounded allegations about the integrity of the upcoming election.

Bolsonaro told them the electronic voting system in Brazil, which has been used without controversy since 1996, was vulnerable. The remarks raised concerns that the populist politician – facing poor polling results – may attempt to discredit the democratic process if he loses in October.