Hungary's usually divided opposition will unite Wednesday for a major rally against Prime Minister Viktor Orban, following what it sees as three years of authoritarian government, AFP reports.
Organisers hope to draw tens of thousands of people onto the streets of Budapest in a show of force against Orban, who they accuse of damaging the economy and undermining democratic structures.
The demonstration, coinciding with a rival rally by Orban supporters, comes six months before elections in the former communist EU member.
It also takes place on the anniversary of the start of Hungary's doomed 1956 anti-Soviet uprising, brutally crushed by Russian tanks, a day that has become a favourite for political rallies.
The opposition protest will bring together for the first time the Socialist party and smaller groups like the Democratic Coalition (DK) and an alliance led by former premier Gordon Bajnai.
"We will show the regime that despite our differences we haven't forgotten that the enemy is Viktor Orban, not each other," said a spokesman for the Together 2014 party, part of Bajnai's amalgamation.
Since sweeping to power in 2010 with a two-thirds majority in parliament for his Fidesz party, Orban has sought to shake up 10-million-strong Hungary with a tidal wave of often controversial legislation.
The 50-year-old premier has been accused at home and abroad of undermining the independence of the judiciary, spooking foreign investors, presiding over a rise in anti-Semitism and trying to muzzle the press.
But despite an Ipsos survey last week showing almost half of Hungarians wanting a new government, as well as some close recent municipal elections, Orban remains popular.
The opposition's sense of unity could quickly fade once the banners have been folded and everyone has gone home, analysts say.
"The opposition don't have an Orban, someone who is a clear leader of not just his own party but almost the entire right-wing," Attila Juhasz, an analyst with the Political Capital consultancy, told AFP.
Socialist leader Attila Mesterhazy and Bajnai, who returned to politics a year ago, both nurse ambitions to be prime minister and neither wants to appear too closely linked with Ferenc Gyurcsany, the most charismatic opposition figure.
Gyurcsany remains controversial after a leaked speech, in which he admitted lying to win an election, sparked riots in 2006. Some in the opposition consider him an electoral liability.
"It's natural that we have differences of opinion, that's why we are in different parties. But we all share the same goal, to rid Hungary of Orban and restore democracy and freedom," Gyurcsany told AFP.