By Krisztina Fenyo and Gergely Szakacs
BUDAPEST, March 15 (Reuters) - Hungarian Prime Minister Viktor Orban sought on Sunday to mobilise voters for what he called an "historic" vote on April 12, while opposition supporters hoping to end the nationalist leader's 16-year rule turned out in droves at a rival rally.
Orban faces what could be his toughest bid for re-election after three years of stagnation, a surge in the cost of living and a pro-EU rival seen by many as a viable alternative.
Both Orban's right-wing Fidesz and centre-right challenger Peter Magyar's Tisza used Hungary's March 15 national day for a show of force as the campaign enters a pivotal stage. Most surveys put Tisza ahead by a wide margin.
Orban has cast the vote as a choice between war and peace, accusing his rivals of plotting to drag Hungary into the war raging in neighbouring Ukraine since Russia's February 2022 invasion, accusations which the opposition denies.
Dismissing his rival's poll lead, Orban said Fidesz should aim to exceed its 2022 election landslide.
"We must win not like we did four years ago but better. We need not as many votes as four years ago but more," he said. "We must score a historic victory, because the next government will have a historic responsibility."
Orban said his supporters' rally was the largest of its kind, filling a main square outside parliament.
Opposition supporters thronged a majestic avenue stretching from near the Danube River to Heroes' Square in one of the largest rallies against Orban, exposing deep rifts in Hungary.
A Fidesz supporter called Orban "Europe's best politician," while some attending Magyar's rally wondered if they had a future in Hungary if Orban gets re-elected.
Orban has long been at loggerheads with the EU over a range of issues, including Ukraine. Defying Brussels, he has maintained cordial ties with Moscow, refuses to send weapons to Ukraine, and says Kyiv can never join the EU.
While most polls have shown a Tisza lead, Fidesz points to surveys showing it on course to victory, though its opponents say these have mainly been conducted by institutes with financial or personal ties to the ruling party.
Magyar has dismissed Orban's campaign as laughable "propaganda", but Tisza has trodden cautiously on Ukraine, saying it opposes any fast-track EU accession for Kyiv and that it would put the issue to a binding referendum if it wins power.
Magyar, speaking in a venue where Orban shot to fame in 1989 by calling for the withdrawal of Russian troops from the country, said Hungary's place was squarely in the European Union and NATO.
"Holding onto power at all costs. It is all that matters to him now," Magyar said of Orban. "Provoking with war, threatening with war, stoking war. This is his ultimate weapon against the Hungarian people."
Some opposition supporters also thought the election would be a watershed moment.
"I think this country cannot bear four more years of Fidesz rule," Noemi Szemerszki said.
(Reporting by Gergely Szakacs; Editing by Gareth Jones and Alexander Smith)
