Budapest edged closer on Friday to a possible withdrawal of its bid to host the 2024 Olympic Games, dealing a potential further blow to global organisers' attempts to find a city to host the event following a number of pullouts.
Hungarian political movement Momentum said had collected more than 266,000 signatures on a petition against the bid, which its leader Andras Fekete-Gyor indicated would be enough to trigger a referendum.
Budapest's Mayor Istvan Tarlos told a news conference earlier that, if a referendum was called, he would "seriously consider" a proposal to withdraw the bid.
The city is competing against Paris and Los Angeles to host the Games, and an event whose costs have risen sharply over the past 20 years.
If it did pull out, it would join Hamburg, Rome and Boston among candidate cities that later abandoned bids.
"The past 30 days have been one of the most magnificent periods in the history of democracy in Budapest," Fekete-Gyor told a news conference after the petition result.
Spokesmen for the bid organisers declined immediate comment, but Prime Minister Viktor Orban's ruling Fidesz party appeared to distance itself from the bid.
Lajos Kosa, a senior Fidesz lawmaker, said the issue was not discussed at a party meeting and the bid was in the hands of Budapest.
Momentum, launched by a group of students born around 1989 when the country's Communist regime collapsed, has collected the signatures over a month-long campaign.
The Budapest Election Office will now rule whether a sufficient number of valid signatures - in broad terms amounting to 10 percent of Budapest's around 1.4 million voters - has been collected to call a referendum.