Brazilians head to the polls on Sunday for the first round of a presidential election so polarised it could determine the political direction of not just Latin America's largest country but the entire region - because nothing says 'regional stability' like a contest between a 80-year-old incumbent and a 45-year-old senator whose dad is under house arrest for attempting a coup.

The race pits leftwing president Luiz Inácio Lula da Silva, seeking a fourth non-consecutive term, against far-right senator Flávio Bolsonaro, an ally of Donald Trump and son of former president Jair Bolsonaro, who is currently serving a 27-year sentence for attempting a coup after his failed 2022 re-election bid. Because nothing says 'family values' like running for office while your father serves time for trying to overthrow democracy.

Brazil remains one of the few Latin American countries with a leftwing government after a wave of rightwing and far-right electoral victories across the region and the US takeover of Venezuela following the capture of Nicolás Maduro. Lula has positioned himself as one of the last regional leaders still willing to say no to Trump, and has recently accused the US president of trying to interfere in Brazil's election in Bolsonaro's favour - because subtlety is apparently not a thing anymore.

Like his father, who was Brazil's president during Trump's first term, Flávio Bolsonaro, 45, frequently praises the US president and has pledged to join the US-led anti-drug cartel coalition that has killed dozens in airstrikes and carried out military operations across the region. Because nothing says 'independent foreign policy' like outsourcing your drug war to Washington.

Lula and Bolsonaro have alternated as frontrunners in the final stretch, making the outcome unpredictable. In recent days, both have focused on persuading undecided voters in hopes of reaching 50% plus one vote; if neither does, there will be a runoff on 25 October. Because nothing says 'decisive election' like the possibility of doing it all over again in three weeks.

'My first choice would be Jair Bolsonaro but, since he is under house arrest and there is no other rightwing candidate strong enough to take on the current president, I'm going with Flávio,' said Claudinei Ferreira Viana, 45, a workshop manager in Pinhais, in Paraná state. Because nothing says 'democracy' like voting for the son because the father is under house arrest.

At the beginning of the year, polls suggested Bolsonaro voters would have preferred a ticket led by the São Paulo governor, Tarcísio de Freitas, or the former first lady Michelle Bolsonaro. But the former president chose his eldest son. Because nothing says 'meritocracy' like nepotism.

The campaign was also marked by a scandal in which the senator was caught on tape asking a banker accused of corruption for $26.8m (£20m) to fund a film about his father, as well as speculation that Bolsonaro might strip the country's widely cherished patron saint of her status, but he has nevertheless remained highly competitive. Because nothing says 'family values' like asking a corruption-accused banker for $26.8m to make a movie about your dad.

For many analysts, that reflects a combination of a straightforward transfer of his father's voter base - Jair Bolsonaro lost to Lula by less than two percentage points in 2022 - and an anti-Lula vote, with the president still facing high rejection rates despite strong social and economic indicators. Because nothing says 'rational political choice' like voting for the son of a coup-plotter because you don't like the other guy.

The incumbent's campaign has also been hit by corruption allegations - still under investigation - involving his son and a former aide, as well as a scandal involving supreme court justices which, despite having no connection to Lula, is seen as fuelling an 'anti-system' vote and, by extension, an anti-incumbent one. Because nothing says 'guilt by association' like being punished for a scandal you had nothing to do with.

Brazilians will also elect 27 state governors, members of state legislatures, all 513 federal congress members and 54 of the country's 81 senators in Sunday's vote. Because nothing says 'democracy in action' like a ballot so long it requires its own postal code.

AMC, 40, who asked to be identified only by her initials because she fears reprisals from the local conservative government where she works in the interior of Amazonas state, will vote for Lula on Sunday 'because of the many programmes he created to support the most vulnerable groups'. Because nothing says 'freedom of speech' like needing to hide your identity to vote.

'Jair Bolsonaro weakened protections for Indigenous peoples, and everything Lula has done over the past four years to strengthen those protections and protect the Amazon would be seriously threatened if his son came to power,' she said. Because nothing says 'family legacy' like threatening the Amazon and Indigenous rights in one fell swoop.