A few days after Bloco de Esquerda (Left Bloc) won 10% of the vote in the Portuguese general elections last month, Joana Mortágua strode through the marble halls of the Portuguese parliament.

Mortágua doesn’t resemble most deputies: she doesn’t wears suits, preferring a T-shirt and sneakers. She’s athletic and gathers her hair into a ponytail. Even after a historic result, she looked relaxed and amused, joking with colleagues that she had too many meetings to go to. Fast-forward a few weeks and her diary is fuller; Mortágua has become one of the most powerful politicians in the country.

Bloco de Esquerda, Portugal’s equivalent to Greece’s anti-austerity Syriza party, is a crucial element in a leftwing alliance which is set to deliver a socialist government. Its sudden rise is also the story of a remarkable turnaround in fortunes which, in a notoriously macho political culture, has been masterminded by four women: the Bloc’s leader, Catarina Martins, deputies Mortágua and her sister Mariana, and Euro-deputy Marisa Matias.

During the past year the quartet have confronted corrupt bankers and businessmen in parliament and won major debates in a country where women are left out of most politics.

In 2009 Martins and Matias discussed how to promote greater prominence for women inside the Left Bloc. The fringe party had existed for 10 years and always emphasised feminism and gender equality. But its charismatic leaders were all men, including Francisco Louçã, Luís Fazenda, Miguel Portas and Fernando Rosas. “The founding male figures of the Left Bloc are feminists, but Marisa and I felt the need to tell them, ‘We want to engage in politics,’ ” says Martins.

The women started to take action to combat the macho traits of a party that had deep roots in Portuguese society. “At the end of our meetings, we count how many times men and women took the stage to speak. Men always speak more than women – but usually they have nothing new to say. Women are more cautious about speaking in public, but when they do they’re adding new ideas or information,” says Joana Mortágua. Martins says the party now trains women in public speaking.

“I encourage younger and shyer women to speak. And sometimes I scold the older male party figures, asking them to resist the temptation to explain what a woman said once she’d finished speaking,” she says.

These strategies paid off in 2012. The party leader, Louçã, stepped aside and nominated a man – João Semedo – and a woman, Martins, to replace him, trying to replicate the leadership model of some far-left parties in Europe.

At first it didn’t work. Martins ended up as leader, but found herself confronting hostility towards the notion of a leading female politician. “She had such a bad time. People would call João Semedo grandpa and Catarina the little granddaughter,” says Matias. Joana Mortágua adds that all the women in the Left Bloc faced sexism. “Our colleagues in other parties treat us in a very condescending way. They always say, ‘Those beautiful girls in the Left Bloc.’ People on the streets mix up our names and call us Catarina Matias, Mariana Martins, Marisa Mortágua, Joana Matias,” she says.

By that time, some leading figures had left the party and in the European elections the Left Bloc lost two deputies. In 2014 Semedo resigned as party leader, leaving Martins in charge. “The shared leadership had meant that neither of them could shine,” says Marina Costa Lobo, a political scientist at the Institute of Social Sciences of the University of Lisbon.

The changes began to bear fruit. “We put women in charge of some areas traditionally associated with men. We chose Marisa Matias as the frontrunner in the European elections and put Mariana Mortágua in charge of the economic dossiers,” says Martins.

Matias became a vice-president of the European United Left in the European parliament and has been chosen as Left Bloc candidate for the Portuguese presidential elections in January. Mariana Mortágua’s role in questioning those responsible for the failure of Banco Espírito Santo – which had a €4.9bn (£3.4bn) bailout after a series of scandals – turned her into a hero. The images of her questioning of Ricardo Salgado, the bank’s former chief executive officer, went viral.

“No one expects such a robust approach from a woman confronting the rich and powerful. The fact that Mariana did that while showing a deep knowledge of the subject granted her a huge respect. She proved her worth,” says Ana Lúcia Teixeira, an expert in women and politics at the Centre for Sociological Studies of the New University of Lisbon.

“People started treating me with respect because of my hard work and stopped making fun of me for being a young liberal woman,” says Mariana Mortágua. During the general election campaign, the faces of the Mortágua sisters and Martins dominated billboards. Martins came across as well prepared and fearless during debates with leaders of other parties – all men and all older. After being mocked for failing to emulate the successes of Syriza, the Left Bloc finally seemed to have found its mojo.

On election night, two winners emerged: the rightwing coalition was re-elected but could only form a minority administration. The real story was that the Left Bloc achieved a landmark haul of half a million votes, making it a pivotal player in negotiations. Martins announced that evening that the Left Bloc would oust a minority rightwing government. There followed weeks of negotiations, during which the Socialist party forged an unprecedented alliance with the Communist party and the Left Bloc.

Last week the alliance forced the minority government to resign. That has left many on the right fearing a return to the revolutionary years that followed the 1974 ousting of the dictatorship. In a febrile atmosphere, the four female figures of the Left Bloc are again coming under scrutiny.

“I didn’t feel a lot of sexism during the campaign, but now it’s worse. It’s much worse to hear someone calling us hysterical on TV,” says Mariana Mortágua. She cites one rant from a commentator on cable TV, who railed against “those four hysterical women. They’re always going against something or someone. I wouldn’t marry any of them, even if for free. I wouldn’t be able to stand such a woman.” On social media, a petition was launched, calling for Mariana Mortágua to pose naked on the cover of Playboy. The slogan chosen by Matias for her presidential candidacy – “one woman for all” – has been given a sexual overtone and transformed into “one woman for everyone”. Catarina Martins’ body has been discussed extensively by journalists, some suggesting she has adopted a more “feminine” haircut and wardrobe and that she is now “dyeing her grey hair”.

“I started to dye my hair some years ago when I realised the grey hair made me look tired. About my clothes – I try to assume that they’re not newsworthy,” she says ironically. “But everyone’s talking about that instead of discussing the fact that the political centre in Portugal no longer exists.”

Old habits die hard. But the four women leading the left into uncharted waters may be about to rip up the old rules of Portuguese politics.