Voting under way across Brazil in tight presidential run-off between Lula and Bolsonaro

Veteran pro-union President Luiz Inacio Lula da Silva suddenly found himself the underdog after right-wing challenger Flavio Bolsonaro took 47% compared to 45% for the incumbent in the October 4 first round.

A combative, three-week run-off campaign turned the political atmosphere electric. The left threw all its energy into securing a comeback, taking to the streets and mobilising on social media – notably with a WhatsApp channel dubbed "Lula's Army" that now boasts 8.5 million subscribers.

Lula, a former labour leader, is seeking a fourth (non-consecutive) term in what he has framed as his final battle.

Bolsonaro, promising a hardline stance on security and improvements in the cost of living, has vowed to "send Lula into retirement". He has also pledged that his first act, if elected, will be to pardon his father, who is currently serving a 27-year sentence – under house arrest – for his role in a 2022 attempted coup d'état, when his supporters stormed parliament in an attempt to cling to power after his own electoral defeat to Lula.

US President Donald Trump, a staunch ally of the Bolsonaro clan, has signaled his support for hard-right movements across Latin America – a region where such forces have secured a string of electoral victories, including in Argentina, Chile, Colombia and Peru.