* Vote expected to give PM third straight term in office
* Orban has campaigned on anti-immigrant message

Prime Minister Viktor Orban launched a last-ditch effort to mobilise supporters in Hungary's parliamentary election on Sunday, as interim turnout ran even higher than in a 2002 vote that consigned him to eight years in opposition.
After an acrimonious campaign in which rightwing nationalist Orban projected himself as a saviour of Hungary's Christian culture against Muslim migration into Europe, all opinion polls put his Fidesz party well ahead.
A strong victory could embolden him to put more muscle into a Central European alliance against the European Union's migration policies. Orban, Hungary's longest-serving post-communist premier, opposes deeper integration of the bloc.
Interim data at 1300 GMT showed voter turnout at 53.64%, a touch higher than the 53.59% in the second round in 2002 under a different election system, when final turnout reached 73.5%. Turnout in the 2014 vote was 61.7%.
Reuters correspondents saw long lines of voters at polling stations. In central London, emigre Hungarians queued for hundreds of metres in the rain to vote, some waiting for more than two hours.
Some pollsters said voter turnout above 70% could signal that the opposition was mobilising supporters efficiently, and might even deprive Fidesz of its parliamentary majority.
"High turnout means, most probably, less mandates for Fidesz than in the previous term," said Peter Kreko, director of think tank Political Capital.
But he added that since all parties, including Fidesz, had mobilised intensively, it did not necessarily mean Orban was threatened with defeat.
Orban has far-right admirers across Europe who like his tough line on migrants and a landslide win would show that his single-issue campaign, arguing that migration poses a security threat, had paid off.
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