Hungary’s Opposition Wins in Budapest and Other Cities

Karacsony called his victory "a lesson on democracy" after Fidesz-backed Istvan Tarlos conceded defeat, media reported.

With most ballots counted, Karacsony, 44, had the support of more than 50 per cent of voters in the capital, compared with just over 44 per cent for Tarlos, 71, mayor of Budapest since 2010.

Preliminary results showed Fidesz dominating in the countryside, where Orban's brand of Christian-conservative "illiberal democracy" remains popular.

It was the first time Fidesz has lost at the ballot box since coming to power nine years ago, though the party's grip on power remains firm with a supermajority in parliament.

The opposition benefited from a last-minute surge in support for Karacsony in relatively liberal Budapest and from the fallout of a sex scandal affecting the Fidesz mayor of a western Hungarian city.

Some commentators have compared Karacsony's victory in Budapest to the result of Istanbul's mayoral race this summer, when triumph for the opposition coalition dealt a blow to the authoritarian rule of Turkish President Recep Tayyip Erdogan.