A six-party opposition alliance that aims to topple Hungary’s Viktor Orbán in elections next year has pulled four points clear of the authoritarian prime minister’s Fidesz party after electing a common leader, according to an opinion poll.

The poll, published late on Wednesday, 10 days after the alliance chose a small-town mayor, Péter Márki-Zay, as its prime ministerial candidate, showed support for the united opposition at 39%, compared with 35% for Fidesz and 23% who were unsure.

Orbán, whose combative brand of national conservatism has transformed Hungary’s political and institutional landscape since 2010, will face a united front of normally squabbling opposition parties for the first time since he came to power.

The alliance of socialists, social democrats, greens, liberals and former far right parties will field a single joint candidate in all 106 of Hungary’s constituencies, targeting what they argue is the regime’s corruption, hypocrisy and advancing authoritarianism.

Previous attempts to unseat Orbán have been driven mainly by a big-city liberal elite, but the ideologically diverse alliance hopes to capitalise on growing dissatisfaction with the prime minister in his conservative rural heartland.

As such, analysts say Márki-Zay, a 49-year-old father of seven who describes himself as a conservative rightwinger and practising Catholic, could prove a smart choice. A former manager for a multinational company, he has degrees in economics, marketing and engineering and has lived in Canada and the US.

He is also an independent, with no links to any mainstream Hungarian party, who rose to prominence by winning a mayoral byelection in Hódmezővásárhely, a southern Fidesz stronghold, in 2018. A year he later won again by a bigger margin.

He has built a nationwide following and a strong network known as the Movement for a Hungary of Everyone (MMM), and presents himself as a palatable choice for both leftwing and conservative voters, with a competent, clean-cut family-man image and Christian faith likely to appeal to swathes of undecided Hungarians.

“He’s honest, and that’s what we’ve been missing for a long time in Hungarian politics,” Robert Molnar, another town mayor and a Márki-Zay ally, told local media. Other analysts say he could potentially appeal both to convinced Orbán opponents, disillusioned former supporters of the prime minister and undecided voters.

Márki-Zay said in a recent interview that his supporters in Hódmezővásárhely come from both left and right. They have “accepted, and also experienced, that with the support of the entire rightwing and leftwing opposition, we can put forward someone who offers an acceptable and credible alternative – even to rightwingers and former Fidesz voters – that can defeat Fidesz,” he said.

He defeated Klára Dobrev of the centre-left Democratic Coalition in an opposition primary this month. She has since pledged to support him in a “coalition of the clean” intended to clamp down on corruption and bridge social divisions.

The popular Budapest mayor, Gergely Karácsony, withdrew from the primaries after finishing second in the first round in September, and has since also urged his liberal supporters to rally behind Márki-Zay.

All are looking to dismantle Orbán’s “illiberal state”, rewrite Hungary’s Fidesz-drafted 2011 constitution and annul a series of new so-called cardinal laws pushed through by the prime minister’s majority that critics say have helped him cement his grip on power.

“Hungary has become a country without consequences. In an election here, the real question most of the time is who is going to steal, and how much,” Márki-Zay told Euronews.

“We believe we must now have an election after which no one will steal. Corruption must be abolished. We want a country where corruption is not organised, but fought.”