JD Vance has railed against the EU, accusing it of blatantly interfering in Hungary’s upcoming elections, even as the US vice-president said he had travelled to Budapest to “help” Viktor Orbán win Sunday’s vote.

Speaking to reporters shortly after landing in Budapest on Tuesday, Vance’s tone was combative as he alleged that the EU was responsible for “one of the worst examples of foreign election interference” he had ever seen.

“The bureaucrats in Brussels have tried to destroy the economy of Hungary,” he said. Gesturing to Orbán, he added: “They have tried to make Hungary less energy-independent. They have tried to drive up costs for Hungarian consumers. And they’ve done it all because they hate this guy.”

Vance, however, made no effort to conceal the reason he had arrived in the country five days before a heated election in which Orbán is facing the possibility of being ousted after 16 years in power. “Of course, I want to help, as much as I possibly can, the prime minister as he faces this election season,” said Vance.

Later, at a campaign rally with Orbán, Vance dialled up Donald Trump, putting his phone’s speaker to the on-stage microphone as the US president offered a glowing endorsement of the Hungarian prime minister. “I love Hungary and I love that Viktor,” Trump told the cheering crowd. “He’s done a fantastic job.”

Hungarians are on Sunday due to cast their votes in a pivotal parliamentary election, in which Orbán is facing an unprecedented challenge from Péter Magyar, a former top member of the ruling Fidesz party.

The election has pitted two distinct versions of Hungary’s future against each other, as Orbán and Fidesz seek to convince voters that the war in Ukraine poses a deep threat to the country and that Orbán is best placed to handle this risk, while Magyar and his Tisza party have urged voters to focus on domestic issues such as economic stagnation, fraying social services and corruption.

Tuesday’s press conference saw Vance drawn into Orbán’s efforts to paint Ukraine as the country’s top threat, with Vance telling reporters that he was aware of Ukrainian intelligence services trying to “put the thumb” on the scale of American elections.

“This is just what they do,” said Vance. He singled out “people in the Ukrainian system” who had campaigned alongside Democrats before the 2024 US presidential election. Hours later, Orbán posted a video to social media in which Vance could be heard praising the Hungarian leader for keeping Europe “strong and prosperous”. Orbán, said Vance, was “one of the only true statesmen in Europe”.

The adulation comes as Orbán’s relationship with the EU has plummeted to new lows, amid clashes on migration, LGBTQ+ rights and, most recently, Orbán’s refusal to sign off on a €90bn loan to Ukraine.

At the evening rally – called a “Day of Friendship” event – Vance delivered further attacks on the EU. “I’m not telling you exactly who to vote for, but what I am telling you is that the bureaucrats in Brussels, those people, should not be listened to,” he said. “Listen to your hearts, listen to your souls, and listen to the sovereignty of the Hungarian people.”

He added: “I see that those who hate Europe the most, who hate its borders, its energy independence, the people who hate its Christian heritage, they hate one man above all others and his name is Viktor Orbán. And if they hate him, it means he’s on your side.”

Vance’s attack on Brussels came amid mounting scrutiny over Budapest’s ties to the Kremlin. On Tuesday – after previous allegations that Russian intelligence agencies, along with disinformation networks with links to Russia, were working to sway the election in Orbán’s favour – it was reported that Orbán had told Vladimir Putin: “I am at your service” in an October call.

On Tuesday, Bloomberg News said it had obtained a Hungarian government transcript of a call that took place between Orbán and Putin on 17 October, in which Orbán reportedly compared the relationship to that of a “mouse” standing ready to help the Russian “lion” as needed.

“Yesterday our friendship rose to such a high level that I can help in any way,” Orbán reportedly told Putin in the call. “In any matter where I can be of assistance, I am at your service.”

Orbán has long been the EU’s most Moscow-friendly leader, maintaining Hungary’s heavy reliance on Russian oil and gas while his foreign minister reportedly regularly updated his Russian counterpart with details of confidential EU meetings and worked to amend the EU sanctions list to Moscow’s liking.

Vance praised Orbán for being a “great example” in Europe on energy security and independence, in what appeared to be a reference to Hungary’s continued reliance on the imports of Russian oil and gas.

Vance said European leaders, in contrast, had made a “huge mistake” in cutting off oil and natural gas from the “east”. A report last month showed that Hungary’s reliance on Russia had increased since the full-scale invasion of Ukraine, with Russia now accounting for 93% of the country’s crude oil imports compared with 61% in 2021.

Vance’s remarks seemingly contradicted US efforts to push its allies to break with Russian energy, with Trump excoriating other EU countries for moving to cease their imports of Russian fossil fuels in response to the war.

The EU, meanwhile, hit back at the claims. “Going back to importing from Russia – a greatly unreliable supplier that is waging an atrocious war against Ukraine – would be a strategic mistake,” said a spokesperson.

In the transcript of the October call revealed on Tuesday, Putin reportedly praised Hungary’s “independent and flexible” stance on his war against Ukraine. “It is incomprehensible to us that such a balanced, middle-ground position only generates counterarguments,” said the Russian president, according to the transcript.

Hungary – which has broken with most EU countries by refusing to help Ukraine with financial assistance or weapons – was also praised by Vance. “Your leadership has been a far, far more important and constructive partner for peace than almost anyone, anywhere else in the world,” the US vice-president told Orbán.

He lauded Orbán – whose “illiberal democracy” has caused the country to plunge in press freedom rankings, face accusations of no longer being a full democracy and become the most corrupt in the EU – as an ally to Trump in the defence of western civilisation.

When asked whether the US administration would be willing to work with another Hungarian government if Orbán failed to win another term, Vance said yes, but that he did not expect a change in government. “Viktor Orbán is going to win the next election in Hungary, so I feel very confident about that and about our continued positive relationship,” he said.

As Orbán and Fidesz lag in the polls, rightwing leaders from around the world have sought to rally behind him, catapulting the election in this central European country of about 9.5 million people on to the global stage as it becomes a wider symbol of the resilience of far-right movements.

On Tuesday, Magyar, whose Tisza party is leading in most polls, directly addressed Vance’s visit to Budapest. “No foreign country may interfere in Hungarian elections,” he said on social media. “This is our country. Hungarian history is not written in Washington, Moscow or Brussels – it is written in Hungarian streets and squares.”