In the run-up to the Irish general election being called on 14 January, public enthusiasm was somewhat lacking. In a post-Christmas slump, the country was half-heartedly preparing itself for a damp-squib campaign. Brexit was in the air, but not on the ground. The housing crisis rumbled on, the health service creaked under stress, but ’twas ever thus. And then, events.

The murder and dismemberment of a teenager exposed Ireland’s drug-related underbelly, making organised crime an election issue early in the campaign. A man sleeping in a tent in Dublin was horribly injured by a canal-side “clean up” vehicle, illustrating the brutality of the homelessness crisis. And Fine Gael, the centre-right party whose outgoing government had a confidence-and-supply arrangement with its rival Fianna Fáil, continued to nurse its own self-inflicted wounds from a poorly proposed and deferred commemoration for the Royal Irish Constabulary.

All of a sudden the campaign became dramatic, with the narrative of a country on the up spinning out of Fine Gael’s control. The party, led by the taoiseach, Leo Varadkar, presented its completed homework to the electorate – pointing to rising employment and claiming that it had the best “team” to manage Brexit negotiations – expecting gold stars. The electorate was unimpressed. Then the polls showed a trend that confounded the political and media establishment: after a very poor showing in the local and European elections last year, Sinn Féin was surging. Game on.

Of course, the election alone isn’t driving change, but it has given life to the feeling that the public is far less satisfied with the outcome of Fine Gael’s period in government than the party expected. Take the central issue of housing, which encompasses astronomical rents, lengthy social housing waiting lists, and an increase in child homelessness and families in emergency accommodation, all alongside luxury construction projects. What was once a housing headache has become an unrelenting, national migraine.

The government’s inability to deal with this major quality-of-life issue, while repeating the line that it was Fianna Fáil that had crashed the economy more than a decade ago, has soured public sentiment. This is compounded by the perception that the gaffe-prone housing minister, Eoghan Murphy, is out of touch and incapable of solving the crisis; as demonstrated when he characterised co-living developments – blocks of expensive studio flats with communal kitchens that are seen as emblematic of the housing crisis – as “very trendy, kind of boutique hotel type place[s]”.

Ireland has the youngest population in Europe, and many of these people have become increasingly politicised in recent years, driven by their participation in the Irish social revolution, which responded to austerity with progressive, grassroots activism and culminated in referendums on marriage equality and legalising abortion. They also mostly refuse to inherit the tribal party affiliations of their parents and grandparents. The loudest applause in one of the leaders’ debates was reserved for Richard Boyd Barrett of the Solidarity-People Before Profit alliance. The electorate is not just looking for change, it’s looking to the left for it.

The main beneficiary of this sentiment is Sinn Féin. A poll published by the Irish Times this week showed Sinn Féin is now the most popular party in the country. Its popularity is not just about being in the right place at the right time, though that’s certainly part of it. Younger voters view Sinn Féin’s association with the IRA as historical. Their republicanism is no longer a turnoff but taps into a new, inclusive patriotism that is characteristic of a generation forming and embracing a modern Irish identity. Mary Lou McDonald is a popular leader, especially with younger women.

Throughout the campaign, Fine Gael has attacked Sinn Féin as weak on crime, and Fianna Fáil as economically “reckless”, but its negative campaigning is falling flat, as the Irish electorate tends to demand civility from politicians and does not respond well to attack ads. In turn, Fianna Fáil has a tricky time attacking Fine Gael, having propped up its minority government for four years.

From left, the Fianna Fáil leader, Micheál Martin, the Fine Gael leader, Leo Varadkar, and the Sinn Féin president, Mary Lou McDonald, during their RTE debate on Tuesday. Photograph: Niall Carson/EPA

While McDonald has successfully portrayed Fianna Fáil and Fine Gael together as the malfunctioning status quo, contrasting it with Sinn Féin’s “new” approach, she faltered under pressure in this week’s leaders’ debate on RTE. McDonald excels at broad brushstrokes and connecting with people, but can be weak on figures and policy detail and, inevitably, the IRA’s past is brought to the fore by journalists and political rivals. The fact that she was included in the debate at all was news. So unexpected was the Sinn Féin surge that RTE had to roll back on its initial format of a head-to-head debate between Varadkar and the Fianna Fáil leader, Micheál Martin. However, Sinn Féin’s relative absence from the media spotlight, with fewer policy launches and media events (a joke among journalists was that McDonald won an early debate between Varadkar and Martin despite not even being there) has allowed a significant section of the electorate to see it as a radical change-maker, whether it is or not.

Will the surge dissipate on election day? Spooked by losing seats in the 2019 local elections, Sinn Féin isn’t running enough candidates to capitalise on its current nationwide popularity. The most likely outcome is some version of a Fianna Fáil coalition, perhaps with Fine Gael – a potentially muted conclusion to a dramatic campaign. A single party, or a combination of parties and independents, requires 80 seats to form a majority or a coalition. A combination of Fianna Fáil and Fine Gael seats would probably exceed that, whereas even if every Sinn Féin candidate were elected – which is highly unlikely – they would still only number 42.

Sinn Féin may privately welcome a strong period in opposition, especially if there’s an unpopular centrist government in power. Disgruntled public sentiment will not simply evaporate, the generational cleavage is very real and demands for change are louder than any party expected. Whatever happens on Saturday, the boundaries of Irish politics are being redrawn.

• Una Mullally is a columnist for the Irish Times