Hungarian Prime Minister Viktor Orbán is set to lose the national election, with opposition leader Peter Magyar set to win a large majority in parliament. It is a bombshell result in an election seen as one of Europe's most consequential this year.

Orbán, the longest-serving leader in the European Union and a longtime ally of President Trump, conceded defeat Sunday night after what he called a "painful" election result, ending 16 years in power.

"I congratulated the victorious party,″ Orbán told supporters in Budapest. "We are going to serve the Hungarian nation and our homeland from opposition as well."

In a Facebook post on Sunday, Magyar said that Orbán conceded to him in a phone call. "Prime Minister Viktor Orbán just congratulated me on the phone on our victory," Magyar wrote.

With 77% of the vote counted, Magyar's party had more than 53% support to 38% for Orbán's governing Fidesz party.

Addressing his supporters earlier Sunday evening, Magyar said that up to 6 million Hungarians had voted in Sunday's election, in a country that has little more than 9 million people. 

Magyar said that despite receiving thousands of reports of election tampering, he was "cautiously optimistic" of victory.

With the Parliament building as the backdrop, large crowds waving the Hungarian flag gathered at the Tisza's election results party near the Danube River and celebrated Magyar's projected win.

"We are celebrating because this is a moment that will go down in history, in Hungarian history, that this regime, this system has been broken ... I think this is a celebration of democracy," a Budapest resident in the crowd told CBS News.

Independent watchdogs and European Union officials have accused Orbán's government of launching a sustained assault on the country's democratic institutions and rule of law since. In the 16 years since he took office in 2010, the country has descended to the rank of the most corrupt country in the European Union, according to the U.K.-based anti-corruption group Transparency International.

At a polling station in Budapest on Sunday, CBS News spoke to a handful of voters, all of whom said they were voting for Magyar and his center-right Tisza party.

"Orban is very anti-EU and pro-Russia, and I think that aligning yourself with, in my opinion, a war criminal, is not good for the country of Hungary," said a 21-year-old who only identified himself as Daniel.

Casting his ballot in Budapest on Sunday, Marcell Mehringer, 21, told the Associated Press he was voting "primarily so that Hungary will finally be a so-called European country, and so that young people, and really everyone, will do their fundamental civic duty to unite this nation a bit and to break down these boundaries borne of hatred."

Orbán has been one of Mr. Trump's closest global allies since the U.S. president was first elected in 2016. The relationship has deepened between the two men over the past decade. The partnership between the Trump administration and Orbán was on full display when Vice President JD Vance publicly campaigned alongside the Hungarian leader in Budapest last week.

European leaders react to results

After Orbán's concession, European Commission President Ursula von der Leyen said a post on X: "Europe's heart is beating stronger in Hungary tonight."

"Hungary has chosen Europe. Europe has always chosen Hungary. Together, we are stronger. A country reclaims its European path. The Union grows stronger," she wrote in another post.

German Chancellor Friedrich Merz on Sunday offered his "heartfelt congratulations" to Magyar.

"I am looking forward to working with you," Merz said in a post on X, adding: "Let's join forces for a strong, secure and, above all, united Europe."

French President Emmanuel Macron offered his congratulations, saying he spoke with Magyar after the win.

"France hails a victory for democratic turnout, the Hungarian people's attachment to European Union values, and for Hungary in Europe," he wrote on X. "Together, we will make Europe more sovereign, for the security of our continent, our competivity and our democracy."

Spanish Prime Minister Pedro Sanchez hailed the results in Hungary as a win for "European values."

"Congratulations to all Hungarian citizens on a historic election," wrote on X. "Looking forward to working together, @magyarpeterMP, for a better future for all Europeans."

British Prime Minister Keir Starmer said the election results were a "historic moment, not only for Hungary, but for European democracy."

"I look forward to working with you for the security and prosperity of both our countries," he posted on X.