SZEKESFEHERVAR, Hungary (Reuters) - Viktor Orban, Europe’s most outspoken nationalist leader, said on Friday Hungary’s future would be decided for decades at an election on Sunday in which he vowed to protect his nation from the “rust” of Muslim migrants.

After a campaign in which Orban has positioned himself as a saviour of Hungary’s Christian culture against Muslim migration into Europe, all opinion polls put his Fidesz party well in the lead for the election.

A third straight term for Orban could embolden Hungary’s longest serving post-communist premier to solidify a Central European alliance against the European Union’s migration policies, and against a deeper integration of the bloc which he opposes.

It would also give a lift to other right-wing nationalists in Central Europe, in Poland and in neighbouring Austria, and expose cracks in the 28-nation EU.

“We will win again on Sunday as we have won battles in the past which looked impossible for many,” Orban told a few thousand supporters waving the national flag in the town of Szekesfehervar, west of Budapest.

“We have built the fence, defended the southern border ... Migration is like rust that slowly but surely would consume Hungary.”

Earlier on Friday he voiced common cause with Poland, whose governing Law and Justice (PiS) party like Fidesz is under fire from the EU over their refusal to take in migrants under a quota system and over their efforts to tighten state control of their courts and media.

“We believe Poles and Hungarians have a common path, common fight and common goal: to build and defend our homeland in the form that we want ... Christian and with national values,” Orban said at the unveiling of a statue marking a 2010 plane crash that killed the Polish president.

Poland’s PiS leader, Jaroslaw Kaczynski, attending the ceremony commemorating the plane crash in Russia in which his twin brother was killed, endorsed Orban ahead of Sunday’s vote.

Orban’s Fidesz, with a firm grip on the media, dominates the public agenda. All polls predict a win for him on Sunday though something short of the landslides of elections in 2010 and 2014.

There is also a slight chance that the fragmented opposition, with formerly far-right Jobbik as the main challenger, could foil a romp to victory and strip Fidesz of its parliament majority.

At a rally in Budapest on Friday, Socialist prime ministerial candidate Gergely Karacsony accused Orban of having abused his strong political mandate.

“There is no other man who had so much power and who has abused it so much,” Karacsony told hundreds of supporters.

Orban, 54, who started out as a young liberal activist in the late 1980s, has transformed Hungary’s democratic fabric in the past eight years with what his critics see as an increasingly authoritarian style.

His government has expanded control over state media and, via business allies, also large chunks of the private media.

Businessmen close to Fidesz and Orban have acquired stakes in major industries like banking, energy, construction, and tourism, enriching themselves on EU funds.

In clashes with Brussels over his policies, he has ruled out taking part in any EU-wide mechanism to settle migrants from the Middle East in Hungary. Orban has declared that Hungary, which has no history of large-scale immigration, should preserve its “ethnic homogeneity.”

Hungarian Prime Minister Viktor Orban delivers a speech at the National University of Public Service in Budapest, Hungary, April 4, 2018. REUTERS/Bernadett Szabo

“INVASION” THREAT

In 2015, even before the peak of Europe’s migration crisis, Orban realised that the threat from what he called “an invasion” by Muslim immigrants struck a chord with a large part of the Hungarian electorate.

His government built a fence on the southern border with Serbia to keep out migrants at a time when hundreds of thousands had walked though Hungary on their way to richer western Europe.

The Fidesz election campaign has vilified U.S. financier George Soros, whose philanthropy aims to bolster liberal and open-border values in eastern Europe, and runs against Orban’s concept of an “illiberal democracy”.

The fierce anti-immigrant campaign has gone down well with around 2 million core voters of Fidesz. According to a poll and estimates by Republikon institute on Thursday, Fidesz could win 113 seats in Hungary’s 199-seat parliament.

However, the polls could be unreliable as one-third of voters are uncertain and many hide their voting preference.

Sitting on a bench in Budapest, enjoying the sun with a cup of coffee in his hand, Istvan Nagy, a 50-year old plumber, said he would vote for Orban as a guarantor of security.

“Of course, Fidesz, Viktor Orban! Why? Because he is the only one who makes me feel secure in this country, this is what I have got used to and I want this to remain,” he said. “We have a job, and money and also the girls are pretty here.”

While Orban has gradually become a nationalist admired by far-right politicians across Europe, he is credited with keeping the budget deficit under control, reducing unemployment and reducing some of Hungary’s debt pile.

His income tax cuts have put the economy on a growth track, with the economy expanding by 4 percent in 2017 and consumption and lending on the rise.

Financial markets have been pricing in a new term for Orban, and have mostly cast aside the chances of a Fidesz defeat.

That could trigger a fall in the forint and government bonds in the event of an upset, traders say.