Hungarians voted on Sunday in closely watched parliamentary elections that could end nationalist Prime Minister Viktor Orban's 16-year stint in power as a self-described "thorn" in the EU's side.
US President Donald Trump has thrown his weight behind the EU's current longest-serving leader, who maintains close ties to Russia. The vote is being closely followed abroad, particularly across the rest of Europe.
Opinion polls suggest the Tisza party of pro-European conservative Peter Magyar, who has promised a "system change", is running well ahead of Orban's.
Both camps have alleged foreign interference during the campaign in the central European country of 9.5 million people. US Vice President JD Vance visited Budapest earlier this week to rally with Orban.
Orban, 62, who is seeking a fifth straight term, has transformed his country into a model of "illiberal democracy", publicly clashing with Brussels over rule of law issues, as well as over support for war-torn Ukraine.
Former government insider Magyar, 45, burst onto the scene just two years ago, amassing support against a backdrop of economic stagnation, despite an electoral system skewed in favour of Orban's Fidesz party.
- 'Last chance' -
"Now is our last chance to choose finally east or west. Do we want to be a normal democracy or turn back east with no point of return?" first-time voter David Banhegyi, 18, told AFP after casting his ballot for Magyar's party Tisza in a leafy part of Budapest as a steady trickle of voters arrived.
After casting his ballot in the capital, Magyar called on Hungarians to vote in a "decisive election".
"We are choosing between East and West, propaganda or honest public discourse, corruption or clean public life, further decline and the complete collapse of public services, or bringing EU funds home and reviving the Hungarian economy," he told reporters.
Orban has increasingly locked horns with Brussels, which accuses him of quashing dissent and eroding the rule of law and has frozen billions of euros in EU funding.
During his visit, Vance attacked the alleged interference in Hungary of Brussels "bureaucrats", while Trump has promised to bring US "economic might" to Hungary if Orban's party secures victory.
After casting his ballot, Orban repeated warnings of a "major crisis" awaiting Europe.
"Fortunately we have a lot of friends in the world. From America to China to Russia and the Turkish world," he said, adding he would not allow Hungary "to be deprived" of its "future and sovereignty" by Brussels.
Maria Toth, a 31-year-old stay-at-home mother of two, told AFP at a Budapest polling station that "it is so important for us that Viktor Orban stays in power".
"I feel Hungary is under siege from so many directions and big powers like Brussels are trying to dictate how we live. If he loses, I worry for my children's future," she added.
Orban has focused on making Ukraine the central topic of his campaign, portraying the neighbouring country, which is fighting off a Russian invasion, as "hostile" to Hungary.
He also vowed to continue his crackdown against "fake civil society organisations, bought journalists, judges (and) politicians".
"If Fidesz wins now, that will clearly mean... a shift towards authoritarianism," Andrea Szabo, a senior research fellow at ELTE University's Centre for Social Sciences, told AFP.
- 'Will of the people' -
Polls, which opened at 6:00 am (0400 GMT), will close at 7:00 pm.
Analysts expect a record turnout of around 75 percent, exceeding the previous high of just over 70 percent.
First results are expected soon after polls close, but if the race is tight the winner might not be declared until ballot counting is completely finished next Saturday, according to the National Election Office.
While the opposition fears Orban may not recognise the election results, the nationalist leader has accused the opposition of "an organised attempt to use chaos" and "colluding" with foreign intelligence.
"The will of the people must always be recognised," Orban said after casting his ballot.
After voting, Magyar called on voters to report suspected vote-buying, intimidation or other violations, while urging calm.
In the lead-up to the vote, a flurry of accusations, counter-accusations and leaks surfaced, including recorded phone conversations that caused EU-wide alarm about Orban's and his foreign minister's close relations with Moscow.