"Putin go to hell. And take Orban with you!" shouted an angry protester at a demonstration in Budapest this week.

The protesters were gathered near a Russia-linked investment bank that critics of Hungarian Prime Minister Viktor Orban call a "Kremlin spy bank."

Rallied by opposition leader Peter Marki-Zay, they chanted "Russians go home!," a slogan used during the anti-Communist uprising in 1956 that was brutally crushed by Soviet troops.

Orban's carefully nurtured ties to President Vladimir Putin have become a lightning rod for the country's embattled opposition since Russia invaded Ukraine, and threaten to finally unseat him at the general election on April 3.

The 58-year-old Orban, who has been in power since 2010 and is bidding for a fourth straight term, still holds a narrow lead. A poll this week gave him 48 percent support to his rival's 46.

But it will not be the romp to victory that Orban enjoyed in 2014 and 2018, when he was shored up by populist economic and anti-immigration policies.

"Many conservative Hungarians have traditionally been anti-Russian, so the invasion could be a red line for many Orban voters," Andras Bozoki, a politics professor at the Vienna-based Central European University, told AFP.

'Eastern opening'

Improving relations with Russia was part of the "Eastern Opening" policy that Orban adopted soon after winning power 12 years ago.

He has met Putin annually, signing deals with Russia's Rosatom to expand a nuclear plant and with Gazprom for a long-term gas import agreement.

In 2014, he praised Russia's "successful" governing system during a speech in which he proudly declared his vision of Hungary as an "illiberal" state.

Prior to the war, he also protested against anti-Russia sanctions and vetoed Kyiv's progress toward NATO membership because of a dispute about language rights for the large ethnic-Hungarian minority in western Ukraine.

Such moves have fuelled accusations that Orban is Putin's "Trojan horse" inside the European Union, an allegation he fiercely denies.

East vs West

As the election looms, Marki-Zay, a technocrat who has focused strongly on an anti-corruption agenda, is framing the vote as a stark choice between East and West.

"Only the EU and NATO can guarantee Hungary's security, not Orban," he told the protesters in Budapest.

They had gathered in front of the International Investment Bank (IIB), majority-owned by the Russian state, which moved its headquarters from Moscow to Budapest in 2019.

It has its roots in the Soviet Union and is often criticized as a vehicle for Russian influence in Central Europe and, potentially, for intelligence gathering.

Bulgaria, the Czech Republic, Poland, Romania and Slovakia have all said they are pulling out of the bank following Moscow's invasion of Ukraine.

Marki-Zay says Hungary should follow suit and also suspend the Rosatom-backed nuclear project.

But Hungarian Foreign Minister Peter Szijjarto says the IIB is not on any EU sanctions list and Hungarians need nuclear power to avoid rocketing energy prices.

Incumbent effect?

The invasion of Ukraine has left Orban struggling to find a coherent response.

He has approved EU sanctions against Russia and condemned the invasion but has refused to condemn Putin.

Hungary supports Ukraine's bid to join the EU but is the only member of the so-called Visegrad Four group — also including the Czech Republic, Poland and Slovakia — that refuses to send military aid to the country.

Orban has also prohibited the transport of lethal aid to Ukraine via its territory.

"We must stay out of this war and not drift into it," he has said.

Orban is bolstered by powerful pro-government media that often echoes Russia-friendly narratives and claims that Marki-Zay is pro-war.

"In a crisis, especially in a war situation, the incumbent effect is strong come election time," said Agoston Mraz, an analyst with pro-government think tank Nezopont.

"Not so much because the governing party gets new voters but because opposition voters lose their enthusiasm for change," he added.

Still, analysts are cautious about drawing early conclusions.

"Orban's Russia policy of the last 12 years has clearly been a strategic failure and his double narrative game during this war could backfire," Daniel Hegedus, a fellow with the German Marshall Fund, told AFP.