Jakarta, Indonesia – Losing presidential candidate Prabowo Subianto is to legally challenge the official result of Indonesia‘s election as hardline conservative groups threaten street protests after incumbent Joko Widodo was confirmed as the winner of last month’s vote.

The Indonesian Election Commission announced the official results in the early hours of Tuesday morning, bringing forward by more than 24 hours an announcement that had been expected on Wednesday.

The commission’s count showed Widodo, popularly known as Jokowi, and his running mate, Ma’ruf Amin, had received 55.5 percent of the votes, compared with 44.5 percent for Prabowo and his running mate, Sandiago Uno. The results closely resemble the unofficial “quick count” results carried out by independent election observers on election day last month.

But the official witness from Prabowo’s team refused to sign the statement of the official results, while campaign spokesman Danhil Anzar Simanjuntak told Al Jazeera that Prabowo’s team did not accept the outcome.

“Officially, we are rejecting the results of the presidential election,” Simanjuntak said on Tuesday morning. “Structural, systematic, massive and brutal fraud has taken place, and it has not been dealt with justly.”

He declined to go into details about the alleged fraud.

Widodo won more than 85 million votes of the 154 million cast on April 17 in the world’s third-largest democracy, the commission said. His party also emerged the winner in the parliamentary elections that took place at the same time.

Prabowo’s side said initially they would not take legal action, but legal director Sufmi Dasco Ahmad told reporters on Tuesday that the team would take their case to the Constitutional Court.

Under electoral law, they have three days to lodge the complaint. Prabowo lost a similar challenge to the results after losing the previous presidential election in 2014.

Arief Budiman talks to reporters after the announcement of the results [Willy Kurniawan/Reuters]

Protest threat

Supporters of Prabowo have said they are planning to hold a rally on Wednesday outside the commission’s office in the capital, Jakarta, to protest against the results. They have called themselves the Brotherhood of 212 Alumni, in reference to the December 2016 protests against Basuki “Ahok” Tjahaja Purnama, the first ethnic Chinese governor of Jakarta who was accused and later found guilty of blasphemy.

Members of the group include the Islamic Defenders’ Front, known by its Indonesian initials as FPI.

During his campaign for the presidency, Prabowo, a former general who has been accused of human rights abuses, found significant support among conservative groups.

Accusations that Jokowi was not a true Muslim ran rampant. Hoaxes alleging that the president would remove religious education in schools, forbid the call to prayer and legalise extra-marital sex and same-sex marriage if returned to power appeared to resonate among voters in the world’s largest Muslim-majority country, even though the claims were false.

“Their movement wants the public to think that Islamic leaders, or leaders supported by Islamic groups, will not win [in elections] because of the fraudulent practices of state actors and the incumbent president,” said Titi Anggraini, the executive director of the Association of Elections and Democracy (Perludem). “They want to present themselves as wronged.”

The election commission said there was no evidence of systematic cheating in the election, while independent observers have said the poll was free and fair.

In his first comments since the announcement of the official results, Jokowi tweeted his gratitude to those who had voted for him.

“Thank you for having faith in us and giving us a mandate,” he wrote in Indonesian. “We will turn your trust into development programmes that are fair and equitable.”

Jokowi later told reporters his government would be “the leaders and protectors of all Indonesians”.

Dina Afrianty, a research fellow at La Trobe University Law School in Melbourne, said Prabowo’s position appeared weak.

“The threat of protest appears genuine, but the call to object to the election result carries far less credibility than the 212 protests,” she told Al Jazeera. “This continuing effort to mobilise people power seems to be running out of steam, and appears to be part of an increasingly desperate and hopeless campaign to impugn the election result.”

In fact, major groups such as Muhammadiyah and Nahdlatul Ulama, Indonesia’s two largest Muslim mass organisations, have distanced themselves from the protest calls.

“This is an important move by Muhammadiyah,” Afrianty added. “Many of its members were previously sympathetic to the 212 [movement], and also broadly in the Prabowo camp. However, this time, Muhammadiyah’s leadership has advised its members that respecting the election outcome is part of their obligation as Muslims to ‘command right and forbid wrong’.”

Razor wire and police trucks deployed outside the headquarters of Indonesia’s election commission amid concerns about street protests called by hardline Islamic groups and losing presidential candidate Prabowo Subianto. [Kate Walton/Al Jazeera]

Heightened security

There was heightened security across Jakarta on Tuesday with a heavy police presence at the commission’s offices and the National Monument, a popular gathering point for protests.

The Indonesian Police put out a warning over fears of attacks by an Islamic State of Iraq and the Levant (ISIL or ISIS) splinter cell known as Jamaah Anshurat Daulah (JAD). Foreign missions, including Australia and the United States of America, have issued safety warnings for Wednesday, citing heightened risks of “terrorism”.

At least 30 individuals have already been arrested over the past week for allegedly planning an attack on the Elections Commission office, located in the heart of Jakarta’s business district. The suspected attackers planned to use remote-detonated devices to cause mass casualties in the crowds, police said during a press conference on May 17.

Police announced that multiple pre-assembled explosives and additional bomb-making materials were found during raids. Among those arrested were seven people who had returned from Syria.

More than 40,000 police and military personnel are being deployed in the capital this week to protect the city from potential violence. The number includes thousands relocated from other parts of Indonesia.

Meanwhile, multiple Chinese-Indonesian women in Jakarta told Al Jazeera privately that they planned on staying at home on Wednesday for their own safety, amid fears of a repeat of 1998’s violence during the fall of then-President Soeharto when minority Chinese-Indonesians were targeted by rioters.

Perludem’s Anggraini believes that even if this week’s protests are small in size compared to the 212 protests, which attracted millions of people, they must be seen as part of a larger movement.

“The May 22 protests have a long-term goal,” she said. “It’s a political investment in future electoral contests. There will be 269 regional elections in 2020, and another presidential election in 2024. Both will be incredibly competitive.”