BUDAPEST, Hungary — Hungary’s incoming prime minister, Péter Magyar, arrived Saturday at the Parliament building to be sworn into office, ending Viktor Orbán ‘s autocratic 16-year rule.

Magyar’s center-right Tisza party defeated Orbán’s nationalist-populist Fidesz in a stunning blow last month, gaining more votes and seats in Parliament than any other party in Hungary’s post-Communist history.

The win will allow Tisza to roll back many of the policies that gave Orbán a reputation among many of his critics as a far-right authoritarian, clamp down on alleged corruption and transform political dynamics within the European Union, where the former prime minister had upended the bloc by frequently vetoing key decisions.

On Saturday, Magyar entered the sprawling neo-Gothic parliament building alongside 140 of his party representatives, controlling 141 seats in Hungary’s 199-seat parliament. Orbán’s Fidesz-KDNP coalition will control 52 seats, down from 135, while the far-right Mi Hazánk (Our Homeland) party will hold six seats.

When the inaugural session is held later Saturday, Orbán will not join in for the first time since Hungary’s first post-Communist Parliament was formed in 1990. After his loss, Orbán said he would focus on rebuilding his nationalist-populist political community.

Magyar, a 45-year-old lawyer who founded Tisza in 2024 after years as an insider in Orbán’s party, has vowed to end official corruption, which he argues has robbed Hungarians of economic opportunity.

The new prime minister has called on Hungarians to attend an all-day “regime-change” celebration outside Parliament to mark his inauguration and the end of the Orbán era.

After he takes his oath at around 3 p.m. local time, Magyar is set to address the crowd outside.

Magyar has promised to repair his country’s ties with the EU, which Orbán had pushed to the breaking point, and to restore Hungary’s place among Western democracies, whose standing had been called into question as Orbán drifted ever closer to Russia.

Unlocking about 17 billion euros ($20 billion) of EU funds for Hungary frozen during Orbán’s time in office over rule-of-law and corruption concerns is among the incoming prime minister’s top priorities. The money is sorely needed to help jump-start Hungary’s struggling economy, which has stagnated for the last four years.

In a sign of that commitment, Tisza officials say they will once again fly the EU flag on the Parliament building’s facade after Orbán’s government removed it in 2014.

Budapest’s liberal mayor, Gergely Karácsony, posted an open invitation to a party by the Danube River later Saturday to celebrate Orbán’s fall and the formation of the new government.

Karácsony wrote in a social media post the party was to express gratitude to Hungarians who have spent years speaking out against Orbán’s system: “Teachers fired, civilians and journalists humiliated, small churches torn apart.”

“We can finally leave this era behind us — but first, let us remember the everyday heroes and express our gratitude with a farewell to the system,” he wrote on Facebook.