A centre-right opposition party focused on rooting out corruption is on course to form Slovakia’s next government after voters ousted the governing leftwing party in a general election marked by a backlash over the 2018 murder of a journalist investigating corruption in the eurozone state.

Vowing to push through anti-corruption measures in the judiciary and police, Igor Matovič, the leader of the winning OLaNO party, galvanised voter outrage over the murder of journalist Ján Kuciak and his fiancee, and the high-level graft their deaths exposed.

The killings – allegedly a hit ordered by an executive with connections to politicians – triggered the largest anti-government protests since communist times and led to the toppling in 2108 of the powerful head of the populist-left Smer-Social Democracy (Smer-SD), Robert Fico, as prime minister.

Fico’s party colleague Peter Pellegrini took over as premier, but he conceded defeat overnight, congratulating Matovič on his decisive victory in Saturday’s vote.

“People want us to clean up Slovakia. They want us to make Slovakia a fair country where laws will apply to everyone,” Matovič told reporters overnight as results showed his party skyrocketing to victory by more than quadrupling its seats. “It was the death of Ján Kuciak and Martina Kušnírová that woke up Slovakia,” he said, vowing that his administration would have “zero tolerance for corruption”.

But according to Juraj Marušiak, a Bratislava-based political analyst, the centre-right OLaNO’s win should not be seen as an outright rejection of populist politics.

He characterised Smer-SD’s ousting as a “victory of rightwing conservative populism” reminiscent of the rise of rightwing populist parties in neighbouring EU countries.

Marušiak said: “In this respect, the situation in Slovakia resembles that of its neighbours, Hungary or Poland or the Czech Republic.” He characterised OLaNO as more of a “heterogeneous, protest-type party” than other governing rightwing parties in the region.

OLaNO took 25.02% of the vote for 53 seats in the 150-member parliament, full results from the Saturday election showed, and is expected to seek coalition partners to clinch a majority of 78 or even a constitutional majority of 90.

Matovič said he expected to open talks with all parties except the outgoing Smer-SD, which won 18.29% for 38 seats, and the far-right Our Slovakia LSNS, which received 7.97% for 17 seats.

Matovič said he would seek talks with the We Are Family conservatives, who scored 8.24% for 17 seats, as well as the liberal Freedom and Solidarity (SaS) party and the fellow liberal For the People party of ex-president Andrej Kiska – which got 13 and 12 seats respectively.

On Sunday, he said he was not sure he would become prime minister, saying it depended if the party could agree with coalition partners and that the president had the power to decide otherwise.

President Zuzana Čaputová, a liberal, said on Sunday she would announce her next steps on Monday, while Matovič earlier said she had already invited him to talks via telephone.

Under the constitution, there is no deadline for the formation of a government. The president is required to call the first session of the new parliament within 30 days after official election results are published.

Matovič, who is an eccentric self-made millionaire and former media boss, set up OLaNO, which is short for “ordinary people and independent personalities, a decade ago. Analysts suggest that Matovič, a media-savvy but unpredictable politician, has a good shot at becoming premier if he manages to unify the splintered opposition.

The murder of Kuciak and his fiancee became a lightning rod for public outrage at graft in public life. The fallout helped propel Čaputová, a liberal lawyer and anti-graft activist, from being unknown to winning last year’s presidential race in the country of 5.4 million people.

The turnout for Saturday’s vote was 65.8%, full results showed – the highest in nearly two decades.