Portugal’s far-right Chega group secured its place as the country’s leading opposition party on Wednesday night, when the final results of this month’s legislative election were confirmed.

After tallying the ballots from abroad, Portugal’s electoral authority awarded two additional seats in the country’s parliament to Chega, and two to Prime Minister Luís Montenegro’s Democratic Alliance coalition, which scored the most votes in the May 18 election.

The center-right therefore remains the largest force in the parliament, controlling 91 of its 230 seats, followed by André Ventura’s ultranationalist group, which will have 60 lawmakers in the hemicycle.

Chega’s new role as the country’s main opposition party confirms the far right’s remarkable growth in Portugal. In six years, the ultranationalist party has gone from having just one lawmaker in parliament to now controlling more than a quarter of the seats in the country’s legislative body.

Portuguese voters responded enthusiastically to a far-right campaign that depicted mainstream parties as being corrupt and incapable of addressing challenges that include chronically low wages, the housing crisis and increased immigration. Expat communities in France, Luxembourg, the U.K. and Brazil overwhelmingly backed Chega, swayed by its pledge to create economic conditions that will allow emigrés to come home.

Chega leader Ventura promised to lead a “smooth and healthy regime change” while addressing supporters on Wednesday, adding that the only people who had any reason to fear him were “those who have spent the past 50 years robbing Portugal.”

The far-right party’s advances in the latest snap elections — the third to be held in three years — came at the expense of the Socialist Party, which lost out to Chega across the southern half of Portugal, including in some districts it had controlled since the 1974 Carnation Revolution.

The socialists held an absolute majority under Prime Minister António Costa as recently as March of last year, but have struggled to find their footing since his resignation in the midst of an influence-peddling scandal and subsequent selection to be president of the European Council. This Saturday, the party is expected to elect former Interior Minister José Luís Carneiro to succeed Pedro Nuno Santos, who stepped down on election night, as their next leader.

Carneiro, one of the few prominent Costa ministers never to have been tainted by scandal, is promising to toe a moderate line.

He is key to collaboration with Montenegro and to ensuring Chega is kept at bay at the national level. To that end, he has already signalled that he will support the incumbent prime minister’s bid to form a new minority government as soon as possible.

Portuguese voters head back to the polls this fall for nationwide local elections in which Chega is expected to grow even further. The far-right party could conquer up to 21 city halls, among them Sintra — the country’s second-most populous municipality — and Montijo, Vila Franca de Xira and Alenquer, all of which have been governed by the left since the fall of the Estado Novo dictatorship.