Hungary is set to vote in a referendum on whether to accept mandatory EU quotas for relocating migrants.
Right-wing Prime Minister Viktor Orban opposes plans to relocate a total of 160,000 migrants across the bloc.
Under the scheme, announced after last year’s migrant crisis, Hungary would receive 1,294 asylum seekers.
Opinion polls suggest strong support for a rejection among those who say they will vote. To be valid, turnout needs to be over 50% of voters.
During the migrant crisis, Hungary became a transit state on the Western Balkan route to Germany and other EU destinations.
In an effort to curb the influx, it sealed its border with Serbia and Croatia. The measure was popular at home but criticised by human rights groups.
Voters will be asked: “Do you want the European Union to be able to mandate the obligatory resettlement of non-Hungarian citizens into Hungary even without the approval of the National Assembly?”
In December Hungary filed a court challenge against the EU plan, which would see relocations over two years.
In a TV interview on Thursday, Mr Orban said: “If there are more ‘no’ votes than ‘yes’ votes, that means Hungarians do not accept the rule which the bureaucrats of the European Commission want to forcefully impose on us.”
“The more migrants there are, the greater the risk of terror,” he added, according to excerpts published by Reuters news agency.
The EU proposal was meant to ease pressure on Greece and Italy, the main entry points for migrants and refugees into the bloc.
Referendum explained, by Nick Thorpe, BBC News, Budapest
Why has the government called it?
Mr Orban closely links migration to terrorism, and what he regards as the dilution of European Christian culture. He wants to play a bigger role on the European stage, as a “champion of the concerns of ordinary Europeans”, against the actions of “an unelected, liberal elite”.
Mr Orban proposes that all migrants be put in a giant refugee camp in Libya, from which they can apply to come to Europe. His policy has proven popular in Hungary. His Fidesz party has regained voters it had lost, and the referendum is a useful organising tool ahead of the next parliamentary elections in 2018.
What is the mood?
Fidesz and the opposition nationalist party Jobbik favour a “No” vote, although Jobbik would privately like Mr Orban to fail. Some opposition parties propose a boycott, others propose spoiling one’s ballot.
The tiny Liberal party urges people to vote “Yes”.
To be valid, over than 50% of Hungary’s 8.3 million electorate needs to cast a valid vote.
What consequences could it have?
Legally none, politically many. As an EU member, Hungary is bound by EU rules. But the bloc’s executive is wavering over compulsory quotas.
Mr Orban would like the satisfaction of Chancellor Angela Merkel falling from power in Germany, the EU abandoning compulsory quotas, and the Visegrad 4 countries (Hungary, Slovakia, Czech Republic and Poland) emerging as a strong power bloc for a Europe of nation-states, against the federal vision of French, German and other leaders.
If the referendum is not successful, however, after throwing so much money and effort into it, Mr Orban will look weak, even foolish.