GUATEMALA CITY — Guatemalan President-elect Bernardo Arévalo waited to be sworn into office Sunday as the old-guard Congress dawdled and delayed the inauguration, sparking angry protests by demonstrators tired of months-long attempts to keep him from taking office.

Supporters who had been waiting hours for a festive inauguration celebration in Guatemala City’s emblematic Plaza de la Constitucion were fed up with yet another delay, and marched to the building where congress was meeting.

They scuffled with lines of riot police, sweeping them roughly out of their way before gathering outside congress demanding legislators stop delaying and name the delegation that must attend the ceremony.

“If they don’t swear him in, we, the people, will swear him in,” said one of the demonstrators, Dina Juc, the mayor of the indigenous village of Utatlàn Sololá.

The inauguration was thus tinged by legal wrangling and tensions, just like almost every day since Arévalo’s resounding Aug. 20 election victory.

Congress, which was supposed to attend the inauguration as a special session of the legislature, engaged in bitter infighting over who to recognize as part of the congressional delegation, as members yelled at each other.

The leadership commission tasked with doing that was packed with old-guard opponents of Arévalo, and the delay was seen as a tactic to draw out the inauguration and weaken Arévalo.

“The commission is taking too long to review (legislators’) credentials, and they are demanding requirements that aren’t even in the law,” said Román Castellanos, a congressman from Arévalo’s Seed Movement.

Arévalo wrote in his social media accounts that “they are trying to damage democracy with illegalities, inconsequential details and abuses of power.”

Samantha Power, administrator of the U.S. Agency for International Development, representing the Biden administration at the inauguration, said via X: “There is no question that Bernardo Arevalo is the President of Guatemala. We call on all sides to remain calm — and for the Guatemalan Congress to uphold the will of the people. The world is watching.”

Luis Almagro, secretary general of the Organization of American States, said in the name of the foreign delegations attending the inauguration that the congress must transfer power to Arévalo and respect the will of the people expressed in the elections.

The still-serving attorney general, Consuelo Porras, had tried every legal trick in the book to put Arévalo on trial or in jail before he could take office. And Arévalo’s party won’t have a majority in Congress and may not even have formal recognition there.

Arévalo is an academic, diplomat and the son of a progressive president from the middle of the 20th century, and his election marked a political awakening in a population weary of corruption and impunity.

“I feel enthusiastic, because we are finally reaching the end of this long and torturous process,” Arévalo said before his inauguration. “Guatemalan society has developed the determination to say ‘no’ to these political-criminal elites.”

But as much as Arévalo wants to change things, he faces enormous obstacles. His anti-corruption stance and outsider status are threats to deep-rooted interests in the Central American country, observers say.

Still, the fact he got this far is a testament to international support and condemnation of the myriad attempts to disqualify him.

For many Guatemalans, Sunday’s inauguration represented not only the culmination of Arévalo’s victory at the polls, but also their successful defense of the country’s democracy.

The inauguration was scheduled to have a festive tone: cumbia and salsa music is planned for a huge celebration in Guatemala’s City’s emblematic Plaza de la Constitución.

That Arévalo made it to within a day of his inauguration was largely owed to thousands of Guatemala’s Indigenous people, who took to the streets last year to protest and demand that Porras and her prosecutors respect the Aug. 20 vote. Many had called for her resignation, but her term doesn’t end until 2026 and it’s not clear whether Arévalo can rid himself of her.

Prosecutors sought to suspend Arévalo’s Seed Movement party — a move that could prevent its legislators from holding leadership positions in Congress — and strip Arévalo of his immunity three times.

On Friday, his choice for vice president, Karin Herrera, announced that the Constitutional Court had granted her an injunction heading off a supposed arrest order.

Prosecutors have alleged that the Seed Movement engaged in misdeeds in collecting signatures to register as a party years earlier, that its leaders encouraged a monthlong occupation of a public university, and that there was fraud in the election. International observers have denied that.

One key was that Arévalo got early and strong support from the international community. The European Union, Organization of American States and the U.S. government repeatedly demanded respect for the popular vote.

Washington has gone further, sanctioning Guatemalan officials and private citizens suspected of undermining the country’s democracy.

On Thursday, the U.S. assistant secretary of state for the Western Hemisphere, Brian A. Nichols, said the aggression toward Arévalo won’t likely stop with his inauguration.