Orban, a eurosceptic nationalist, has carved out a model of an "illiberal democracy" seen as a blueprint by Donald Trump's Make America Great Again (MAGA) movement and its admirers in Europe.
But many Hungarians have grown increasingly weary of Orban, 62, after three years of economic stagnation and soaring living costs as well as reports of oligarchs close to the government amassing more wealth.
Opinion polls over the last two weeks have shown Orban's Fidesz party trailing Peter Magyar's upstart centre-right opposition Tisza party by 7-9 percentage points, with Tisza at around 38-41 per cent.
Voting for the 199-seat parliament is being closely watched in Brussels, with many EU peers criticising Orban, a friend of Russian President Vladimir Putin and a close Trump ally, over what they say is an erosion of Hungary's democratic rule, media freedom and minority rights.
For Hungary's eastern neighbour Ukraine, an Orban defeat could mean the unblocking of a 90-billion-euro European Union loan vital for Kyiv's war effort. It would also deprive Russia of its closest ally in the EU.
Orban has cast the election as a choice between "war and peace". During campaigning, the government blanketed the country with signs warning that Tisza leader Magyar would drag Hungary into Russia's war with Ukraine, something he strongly denies.
"I am looking forward to Sunday's election with the best hope," Orban told supporters in his birthplace Szekesfehervar.
"If we know ourselves well, if we know our country well and if we know our own people well, then I must say Hungarians will vote for safety on Sunday," he added.
Orban has won public endorsements from the Trump administration - culminating in a visit to Budapest by Vice President JD Vance last week - as well as from the Kremlin and far-right leaders in Europe. But his campaign has been shaken by media reports alleging that his government colluded with Moscow.
Orban, who denies any wrongdoing, says his goal is to protect Hungary's national identity and traditional Christian values within the EU and its security in a dangerous world. Meanwhile, former Orban loyalist Magyar, 45, has tapped into discontent over alleged state corruption and falling living standards, with young voters particularly eager for change.
To address a popularity rating of just 8 per cent among under-30s, Orban has scrapped income tax for the youngest workers and launched a subsidised mortgage scheme to help first-time buyers onto the housing ladder amid the EU's steepest rise in house prices under his rule.
But Magyar's offer of change appears to resonate more.
In a final push in the eastern town of Miskolc on Friday, Magyar said: "This will be a referendum... about our country's place and our country's future."
Analysts caution that the outcome of the vote remains uncertain, citing the number of undecided voters, a redrawing of the electoral map in favour of Fidesz and a high proportion of ethnic Hungarians in neighbouring countries, who mostly support the ruling party.
If Tisza does win, unwinding the legal and institutional changes Orban has made may prove a daunting task for a new government if it has a simple majority in parliament.
with DPA
