Karacsony

"There is no money to protect Lake Velence, but there is 70 billion forints for the megalomaniacal desires of a Christian-Democrat politician," Karacsony wrote on Facebook.

"I was a village boy, coming from the heartland, where people worked and struggled to survive. Like my parents. And it is here where I learnt to love and appreciate this land," he declared in a somewhat amateurish Facebook video.

Balazs Furjes, state secretary for the development of Budapest, countered by pointing out that at least Orban speaks good English, while Karacsony still has to give interviews to the foreign media via an interpreter and cannot communicate with counterparts at international conferences due to a lack of basic language skills.

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.