Updated

Hungarians will vote Sunday in a referendum which Prime Minister Viktor Orban hopes will give his government the popular support it seeks to oppose any future plans by the European Union to resettle asylum seekers among its member states. Here's a look at what's at stake:

WHAT ORBAN WANTS

Orban wants to stop the influx of large numbers of Muslim migrants into Europe, arguing they threaten Hungary and Europe's Christian identity and culture. Midway through his third term as prime minister, he suggested last week that the EU should build a "gigantic refugee city" in Libya, to where migrants would be deported from Europe to file their asylum claims.

Orban says the EU needs to strengthen its borders to keep out migrants, like Hungary did last year by building fences on its southern borders with Serbia and Croatia.

The referendum's question is "Do you want the European Union to be able to prescribe the mandatory settlement of non-Hungarian citizens in Hungary even without the consent of Parliament?"

Orban says "no" votes favor Hungary's sovereignty and independence. He also hopes popular pressure will encourage other EU countries to take similar steps. Critics say poll results showing rising xenophobia and anti-migrant feelings among Hungarians are linked to the government's referendum campaign.

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VOTER TURNOUT

At least 50 percent plus one of Hungary's 8.27 million voters need to cast valid ballots for the referendum to be valid.

Despite an unprecedented barrage of government billboards, advertisements and personal appearances by ministers and lawmakers nationwide urging people to vote, polls show validity is by no means assured, even though "no" votes are expected to be in the large majority.

The far-right Jobbik party supports the government's anti-migrant position, while most of the other opposition parties and many civic groups are asking voters to either stay home on Sunday or cast invalid ballots.

"It's important to show as a citizen that you want to take part," says Marta Pardavi, co-chair of the Hungarian Helsinki Committee advocacy group. "However, given the vile nature of this referendum question, we are calling for people to cast an invalid vote."

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MIGRANTS? UFOs?

Nearly 400,000 migrants passed through Hungary last year, making their way toward Western Europe. Yet, the criticized razor-wire fences and new expulsion policies have proven effective. During the first four weeks of September, police reported either zero or just one migrant breaching the border area on 12 different days. Last year, Hungary granted asylum to only 508 refugees and a similar number is expected this year.

The satirical Hungarian Two-Tailed Dog Party is putting up posters and distributing leaflets mocking the referendum. One of their slogans is that the average Hungarian sees more UFOs in his or her lifetime than migrants.

For the record, Hungary's Federation of UFO Research says it receives about two dozen reports a year of UFO sightings across the country.

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THE FEAR FACTOR

The disadvantaged Roma minority, struggling pensioners, young families with children and people living in municipal housing are among those being warned repeatedly of what could happen if Hungary is required to take in refugees.

According to government officials, they may face subsidy or pension cuts, become victims of terrorism and violent acts or be forced to give up their homes if that happens.

The government, assisted by state television, is constantly rehashing often months' old stories about migrant attacks.

"The image of large migrant groups nearly 'darkening the sky' last year is still present in many people, no doubt reinforced by the government propaganda," says Attila Tibor Nagy of the Center for Fair Political Analysis. "The government is also assisted by the attacks in Germany and France, which it very much likes to invoke to show that migrants are dangerous."

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HOW MUCH?

The referendum's technical costs, including printing the ballots and manufacturing ballot boxes, total 4.9 billion forints ($17.8 million). The government says it will reveal how much it spent on the billboard and media campaign after the vote, but partial data shows expenditures of at least 13 billion forints ($47.3 million).

In contrast, the Two-Tailed Dog Party and a few other opposition groups are working with campaign budgets of around $100,000, gathered from small donations.

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WHAT'S NEXT?

The government has not said what consequences a valid referendum supporting its position will have. It has mentioned possible amendments to the constitution but is shying away from specifics. Government spokesman Zoltan Kovacs brushed off suggestions that an invalid referendum would hurt Orban, saying a large number of "no" votes would be enough to bolster the official position against the refugee quotas even with a low turnout.

"The referendum can never become a failure," Kovacs says. "Full stop."

But Jobbik president Gabor Vona says Orban should resign in case of an invalid ballot and former Socialist Prime Minister Ferenc Gyurcsany says it would weaken Orban's "infallibility."

"Brussels has already priced in the referendum and knows well that Hungarian public opinion does not like the migrants," said Csaba Toth, strategic director of the Republikon Institute think tank. "Domestically, nonetheless, a low turnout would be a serious defeat for the prime minister, especially after such a huge campaign."