Brazil’s far-right senator Flavio Bolsonaro has refused to concede defeat in Sunday’s presidential election after a close race saw incumbent leftist president Luiz Inacio Lula da Silva win an historic fourth term.

Bolsonaro, the son of imprisoned ex president Jair Bolsonaro and ally of Donald Trump, said he would ask for the result to be annulled after a Lula-appointed Supreme Court justice extended voting by two hours over transport irregularities.

“It is impossible to recognize the election results, given the circumstances under which things unfolded,” Bolsonaro told journalists.

Yet the scale of the loss, which saw Bolsonaro trailing Lula by over 4 million votes, makes it unlikely his efforts to annul the vote will succeed, analysts said.

With 100 per cent of votes counted, 80 year-old Lula took a 51.79 per cent share of the vote against his 45 year-old rival’s 48.21 per cent. Analysts said high voter turnout may have helped Lula snatch victory from the jaws of defeat, on the eve of his 81st birthday.

Bolsonaro’s petition is undermined by the fact that his campaign also sought a voting extension due to heavy rains in the conservative-leaning south.

But his refusal to concede could nevertheless spark a wave of protests in a country where faith in the electoral system, and in judicial independence, has been strained in recent years, observers say.

Jair Bolsonaro, who served as president from 2019 until 2020, plunged Brazil into a deep democratic crisis after the election in 2022, when his supporters stormed government buildings in protest against the result. He later received a 27-year sentence for plotting a coup.

Lula’s victory over the weekend defied polls, precedent and global anti-incumbent sentiment to put the brakes on a wave of right-wing election victories across Latin America.

The result will disappoint the Trump administration, whose State Department led a campaign to return the Bolsonaros to power.

Financial markets also expressed initial concerns at the shock result. A Tokyo-listed exchange-traded fund tracking Brazil’s Bovespa index dived nearly 15% in Asia trade on news of Lula’s victory.

Lula had trailed Bolsonaro in the first round, but managed to convince voters to come out for him in the runoff.

Speaking at a hotel in São Paulo late on Sunday, he took a conciliatory tone.

“I won’t speak of national unity, because that doesn’t always fit the reality of this country. No one is obliged to like the elected president, but he was put in place to govern for everyone,” Lula said.

Lula’s fourth term could be his most difficult yet, after Brazil elected its most conservative Congress since returning to democracy in the 1980s.

Combined, Bolsonaro’s Liberal Party and allied parties could control over 280 seats in the lower house and up to 50 seats in the Senate, enough for comfortable opposition majorities in both chambers.

Lula faces an economy that his government forecasts will grow just 2.3% next year, adding to fiscal concerns tied to high interest rates and public debt that has risen past 82% of GDP, the highest since the pandemic.

Canadian prime minister Mark Carney said of the result: “The relationship between Canada and Brazil has flourished under our partnership.

“Let’s seize this opportunity to make it even stronger, together — to create major new trade opportunities, protect the environment, and build greater prosperity for both our peoples.”

Mexican president Claudia Sheinbaum said: “Long live democracy, the people of Brazil won.”