Brazil’s Luiz Inácio Lula da Silva was sworn in as president on Sunday, and in his first address expressed optimism about plans to rebuild while pledging that members of outgoing Jair Bolsonaro’s administration will be held to account.

Lula is assuming office for the third time after thwarting far-right incumbent Bolsonaro’s reelection bid. His return to power marks the culmination of a political comeback that is thrilling supporters and enraging opponents in a fiercely polarized nation.

“Our message to Brazil is one of hope and reconstruction,” Lula said in a speech in Congress’ Lower House after signing the document that formally instates him as president. “The great edifice of rights, sovereignty and development that this nation built has been systematically demolished in recent years. To re-erect this edifice, we are going to direct all our efforts.”

Sunday afternoon in Brasilia's main esplanade, the party was on. Tens of thousands of supporters decked out in the red of Lula’s Workers’ Party cheered after his swearing in.

They celebrated when the president said he would send a report about the prior administration to all lawmakers and judicial authorities, revoke Bolsonaro's “criminal decrees” that loosened gun control, and hold the prior administration responsible for its denialism in the face of the COVID-19 pandemic.

“We do not carry any spirit of revenge against those who sought to subjugate the nation to their personal and ideological designs, but we are going to ensure the rule of law," Lula said, without mentioning Bolsonaro by name. "Those who erred will answer for their errors, with broad rights to their defense within the due legal process.”

Lula’s presidency is unlikely to be like his previous two mandates, coming after the tightest presidential race in more than three decades in Brazil and resistance to his taking office by some of his opponents, political analysts say.

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The leftist defeated Bolsonaro in the Oct. 30 vote by less than 2 percentage points. For months, Bolsonaro had sown doubts about the reliability of Brazil’s electronic vote and his loyal supporters were loath to accept the loss.

Many have gathered outside military barracks since, questioning results and pleading with the armed forces to prevent Lula from taking office.

His most die-hard backers resorted to what some authorities and incoming members of Lula’s administration labeled acts of “terrorism” – which had prompted security concerns about inauguration day events.

Lula will have to navigate more challenging economic conditions than he enjoyed in his first two terms, when the global commodities boom proved a windfall for Brazil.

At the time, his administration's flagship welfare program helped lift tens of millions of impoverished people into the middle class. He left office with a personal approval rating of 83%.

In the intervening years, Brazil’s economy plunged into two deep recessions — first, during the tenure of his handpicked successor, and then during the pandemic — and ordinary Brazilians suffered greatly.

Lula has said his priorities are fighting poverty, and investing in education and health. He has also said he will bring illegal deforestation of the Amazon to a halt. He sought support from political moderates to form a broad front and defeat Bolsonaro, then tapped some of them to serve in his Cabinet.

In his first act as president Sunday, Lula signed a decree to tighten gun control and set a 30-day deadline for the comptroller-general’s office to evaluate various Bolsonaro decrees that placed official information under seal for 100 years. He also signed a decree that guaranteed a monthly stipend for poor families, and reestablished the mostly Norway-financed Amazon fund for sustainable development in the rainforest.

Claúdio Arantes, a 68-year-old pensioner, carried an old Lula campaign flag on his way to the esplanade. The lifelong Lula supporter attended his 2003 inauguration, and agreed that this time feels different.

“Back then, he could talk about Brazil being united. Now it is divided and won’t heal soon,” Arantes said. “I trust his intelligence to make this national unity administration work so we never have a Bolsonaro again.”

Read more: Brazil election: Lula defeats Bolsonaro to become president again

Given the nation’s political fault lines, it is highly unlikely Lula ever reattains the popularity he once enjoyed, or even sees his approval rating rise above 50%, said Maurício Santoro, a political science professor at Rio de Janeiro’s State University.

Furthermore, Santoro said, the credibility of Lula and his Workers’ Party were assailed by a sprawling corruption investigation. Party officials were jailed, including Lula — whose convictions were later annulled on procedural grounds. The Supreme Court then ruled that the judge presiding over the case had colluded with prosecutors to secure a conviction.

Lula and his supporters have maintained he was railroaded. Others were willing to look past possible malfeasance as a means to unseat Bolsonaro and bring the nation back together.

“I always wanted to go the inauguration, I didn’t think I would have a chance to see Lula there after he was jailed,” said Tamires Valente, 43, a marketing professional from Brasilia. “I am very emotional, Lula deserves this.”

But Bolsonaro’s backers refuse to accept someone they view as a criminal returning to the highest office. And with tensions running hot, a series of events has prompted fear that violence could erupt on inauguration day.

On Dec. 12, dozens of people tried to invade a federal police building in Brasilia, and burned cars and buses in other areas of the city. Then on Christmas Eve, police arrested a 54-year-old man who admitted to making a bomb that was found on a fuel truck headed to Brasilia’s airport.

He had been camped outside Brasilia’s army headquarters with hundreds of other Bolsonaro supporters since Nov. 12. He told police he was ready for war against communism, and planned the attack with people he had met at the protests, according to excerpts of his deposition released by local media.

Bolsonaro finally condemned the bomb plot in a Dec. 30 farewell address on social media, hours before flying to the U.S.. His absence on inauguration day marks a break with tradition.

Instead of Bolsonaro, a group representing diverse segments of society performed the role of presenting Lula with the presidential sash to Lula atop the ramp of the presidential palace. Across the sea of people standing before the palace, supporters stretched a massive Brazilian flag over their heads.

Speaking to the crowd, Lula listed shortfalls in government funds that will affect the Brazilian people. He said that, according to the transition team’s report on Bolsonaro’s government, textbooks haven’t been printed for public schools, there are insufficient free medications and COVID-19 vaccines, the threat looms of federal universities shutting down, and civil defense authorities cannot work to prevent disasters.

“Who pays the price for this blackout is, once again, the Brazilian people,” he said, and was promptly met by a chant from the crowd: “No amnesty! No amnesty! No amnesty!”