BUDAPEST -- Hungarian Prime Minister Viktor Orban has claimed victory for his long-ruling Fidesz party after European and local elections on June 9, but a former loyalist mounting a more EU-friendly challenge said his new party's success marked the start of a political breakthrough.
Orban's national-populist Fidesz party won the European voting with 44 percent, with nearly all the votes counted, but lost one of its seats in the European Parliament as defector Peter Magyar's fast-rising Respect and Freedom (Tisza) party appeared to control nearly 30 percent with counting nearly complete early on June 10.
Fidesz will still hold 11 of Hungary's 21 European Parliament seats, but Tisza looked set to win seven of its own MEP mandates and further its softer line in contrast to Orban's near-constant feuding with Brussels.
Tisza's rise appeared to erode Fidesz's base among voters slightly but dealt an even heavier blow to the longtime center-left opposition leader, the Democratic Coalition (DK).
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Explainer: Magyar Emerges As Challenger To Orban In European Elections In Hungary
But the broader opposition appeared to hold onto many of the mayoral posts it grabbed in 2019.
In a neck-and-neck race for the mayorship of the capital, Budapest, leftist-green incumbent Gergely Karacsony appeared to hold a lead over the Fidesz-backed David Vitezy of just hundreds of votes with 95 percent of the more than 700,000 votes counted and a recount almost certain.
Elections officials reported record-high turnout, with more than 57 percent of registered voters casting ballots at 10,199 polling stations.
Orban responded to his party's worst showing in the European voting amid the relatively high turnout by saying there were two elections and his party won them both.
"Today we defeated the old opposition, we defeated the new opposition, and it doesn't matter what the current opposition is called, we will always defeat it again and again," Orban, who has governed with a parliamentary supermajority since 2010, said in his election-night speech.
But Magyar congratulated his seven successful candidates for the European Parliament and hailed mandates in 10 local assemblies in the capital.
"What is apparent is that this is the Waterloo of the Orban power machine, the beginning of the end," the 43-year-old lawyer who split from Fidesz in February to campaign on eliminating corruption said.
"What happened here is a political ground-breaking, no matter how you twist it," Magyar said. "What happened here in the last two months? Lies and truth confronted each other."
Orban's Fidesz party is not affiliated with any group in the European Parliament but it hoped to benefit in the election from a rise in far-right sentiment across the continent.
The number of far-right lawmakers in the European Parliament increased sharply after the vote, according to initial projections.
Magyar's party has presented itself as a more centrist and constructive alternative to Orban's brand of "illiberal" populism.
Magyar has said he will join the center-right European People's Party (EPP), which is set to be the largest grouping in the European Parliament.
Orban has angered many leaders in the European Union with perceived attacks on democracy and the bloc's founding principles and inclusivity, his opposition to EU sanctions on Russia and military aid for Ukraine, and his close ties to Russian President Vladimir Putin.
The Fidesz campaign relied heavily on Hungarians' fears of being drawn into the war in neighboring Ukraine.
WATCH: RFE/RL asked voters in Budapest about the ruling Fidesz party's campaign suggesting that its political rivals would draw Hungary into war.
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Can EU Elections Make 'Peace'? Hungarian Voters Divided Over Government Campaign
The election was also a test for the controversial Sovereignty Protection Office (SZH), established in February and which has waded into the campaign to publicly denigrate individuals and groups and criminalize candidates over accusations of foreign funding and influence.
Magyar has served in the Foreign Ministry and in Hungary's permanent representation to the EU. Until 2023, he was married to Judit Varga, a prominent Fidesz member and the former justice minister.
He emerged as a challenger after his ex-wife became embroiled in the case of a presidential pardon for an accessory to serial child sexual abuse that cost former President Katalin Novak her job.
Hungary's next general elections are scheduled for 2026.