BUDAPEST (Reuters) - Hungary’s main opposition Jobbik party has launched a crowd funding campaign to raise money for a state audit authority fine that it said could cripple it in the run-up to 2018 elections.

Hungarians will vote for a new Parliament in April and Prime Minister Viktor Orban’s populist Fidesz party is far ahead in the polls, with Jobbik its nearest rival.

Jobbik, once on the far right, has turned toward the center and in the past year campaigned nationwide against Orban, whom they depicted as the leader of a criminal gang on thousands of billboard ads.

Orban has rejected corruption charges, saying he has spent his entire life in politics and his financial standing was “an open book”.

The State Audit Office (ASZ) earlier this week ruled that the party had purchased the posters far below market prices, breaching rules on political funding. The ASZ slapped Jobbik with a 663 million forint ($2.5 million) penalty.

Jobbik said it has no money to pay the fine. It has 15 days to respond before the ASZ ruling, which cannot be appealed in court, becomes final.

“The ASZ, acting as a court-martial in the manner of the darkest dictatorships, levied on Jobbik a fine whose only real aim is to block the party from running at the elections,” Jobbik said in a statement on its website.

“This is the first step in the final eradication of what is left of Hungarian democracy.”

ASZ Chairman Laszlo Domokos is a former Fidesz lawmaker, while Chief Prosecutor Peter Polt, whose office worked with ASZ on the Jobbik case, is a former Fidesz member twice appointed to his post by Fidesz-dominated parliaments.

The ASZ was an independent and non-political body, its spokesman Balint Nemeth said.

“The prosecution does its job independently, in accordance with the laws,” prosecution spokesman Geza Fazekas said.

“The prosecution did not participate in the ASZ probe in any way,” he said.

He added that the ASZ asked the prosecutors to investigate whether Jobbik blocked auditors from reviewing its files. That investigation has a March 6 deadline.

“Laws apply to everyone, and Jobbik is no exception,” Fidesz spokesman Balazs Hidvegi said. “Jobbik must obey the law, and if they do they will have no problems.”

The audit crackdown triggered broad criticism.

Miklos Ligeti, a director at anti-corruption watchdog Transparency International, said Fidesz has been by far the largest beneficiary of undue price advantages on services that was the basis of Jobbik’s fine.

2014 election ads cost Fidesz at least 4 billion forints at list prices, about four times the legal limit, Ligeti said based on their own calculations. Fidesz said on its disclosures it had spent 984 million forints.

Other parties, including Jobbik, overshot their 2014 limit by 40-50 percent at most, he estimated.

“The auditors have clearly got on Jobbik’s case, as they should,” Ligeti said. “They should do the same with every other party but clearly don’t. Which one they strike down and which they spare seems to be a party political decision.”

Fidesz was not immediately available to comment on the Transparency International calculations.

For the campaign Jobbik used billboards owned by a tycoon named Lajos Simicska, once a key ally of Orban who fell out with the premier in 2015. Orban says Simicska hijacked Jobbik. Both the party and the tycoon deny this.

($1 = 267.83 forints)