Northern Irish politics are on the brink of an inflection point on 5 May if the latest polling proves correct, ending a century in which the largest party in Northern Irish politics has come from the unionist community. Instead Sinn Féin, a party that campaigns for a united Ireland, seems likely to win a historic victory, becoming the largest party in Stormont. Sinn Féin is historically associated with the IRA, but after a ceasefire its politicians have committed themselves to peaceful participation in politics through the Northern Ireland assembly since the return of a devolved legislature in 1998. The latest Northern Irish opinion poll puts Sinn Féin on 26% of the vote, seven points ahead of the Democratic Unionist party on 19%. The DUP fiercely defends Northern Ireland remaining in the UK. It would be only the second time in the region’s history that a nationalist party (one advocating a united Ireland) will have gained the most first-preference votes*, and the first time nationalists have won the most seats and the right to appoint the first minister. With the Scottish National party dominant in Holyrood, a Sinn Féin win would leave both Scotland and Northern Ireland’s legislatures led by parties advocating an exit from the UK. Looking at elections through Northern Ireland’s 101-year history shows just how significant a Sinn Féin win would be. An emotional event “For many [Sinn Féin voters] it will be an emotional and significant event which they possibly felt they would never see in their lifetime,” says Dr Marisa McGlinchey, an assistant professor in political science at Coventry University. From the other perspective, it is a shock to the entire foundation of Northern Ireland: “Northern Ireland was created as a Protestant state for Protestant people,” says Dr Nicolas Whyte, a visiting professor at the University of Ulster and senior director at the consultancy APCO Worldwide. “To have a nationalist first minister … means that there has been a historical shift.” Although Sinn Féin’s seven-point lead is the topline from the opinion polls, the growth of the middle ground is also important, with an increased vote for the cross-community Alliance party likely to be a feature of this election. However, unionist parties (those advocating staying in the UK) will still have a larger number of votes (41%) than nationalists (37%), according to the poll. But even together, unionist voters account for less than half of the electorate. And as the chart above shows, a four-point difference is a stark change to the 20- to 30-point lead unionists have registered in previous stages of Northern Irish history. In practical terms the shift is less significant. The Northern Ireland assembly is designed for a power-sharing coalition and Sinn Féin has been in government since 1999, and has held the position of deputy first minister since 2007. Power sharing also means that governments need the support of both communities. So if the DUP does not like the election result in May, the party has the power to block the formation of a new executive. Despite this, a Sinn Féin win will be hugely symbolic in showing how the ground has shifted. Votes to seats One glimmer of hope for the DUP comes from the Northern Ireland’s voting system for the assembly. Transferable voting allows the electorate to list a second preference, which comes into play if the first-preference party is knocked out. Unionists voting for the Traditional Unionist Voice, for example, may list the DUP as their second preference, meaning the DUP could pick up extra votes and vice versa. Still, it will be hard for the DUP to make up a seven-point shortfall. Proportional representation in Northern Ireland puts seat percentages closer to vote percentages than in the UK general election. For example, in the 2017 assembly elections, the DUP won 28.1% of first-preference votes, taking 28 of 90 seats (31%). DUP loss or a Sinn Féin win? It is the DUP itself that has brought its two-decade dominance of Northern Irish politics to an end, argues Dr James Pow, a lecturer at the school of history, anthropology, philosophy and politics at Queen’s University Belfast. Recent missteps include an embarrassing leadership crisis last summer when the party ousted two leaders in as many months. There was also the DUP’s miscalculations over Brexit that resulted in the Irish Sea border, which has pushed Northern Ireland further away from the rest of the UK than at any stage in the past 100 years. This is a DUP loss, not a Sinn Féin gain, Pow says. “While polls suggest that Sinn Féin is on course to emerge as the largest party, they also suggest its performance may be weaker than in other recent assembly elections,” he says. “At this stage it is not the case that Sinn Féin is experiencing a surge in support; it is that the DUP is seeing a slump.” This is no blip, McGlinchey argues, but a longer-term trend of demographic growth in the nationalist vote. She also makes a point about a difference in political vision since the Good Friday agreement. “Nationalism has largely viewed the political process in Northern Ireland as achieving gains and advancing equality. For some it is a stepping stone to a united Ireland,” she says. McGlinchey contrasts that with a more anxious focus in unionist politics, saying: “Unionism has focused on losses and a feeling that the place of Northern Ireland within the UK is less secure.” This feeling of insecurity may be justified, but may not be enough to hold voters for the next few decades. The path to a united Ireland With Sinn Féin also the largest party by first-preference votes in the Republic of Ireland, following the 2020 election, it is in the unusual position of being in the lead on both sides of the border. However, the party is not in power in Dublin, because of a coalition formed by Fine Gael and Fianna Fáil. In the Republic of Ireland, voters are consistently in favour of a united Ireland, although have reservations about how it would be implemented. A big drive from Sinn Féin in March promoted Irish union to European diplomats (paywall) as an idea whose time had come – and conveniently – a solution to the impasse over Northern Ireland protocol. Under the Good Friday agreement, a simple majority of more than 50% is needed in a referendum for Northern Ireland to leave the UK. But the Westminster government needs to approve the referendum first. In polls, a majority of people in Northern Ireland have backed staying in the UK. The percentage has reduced since Brexit, but is still ahead of support for a united Ireland. In a University of Liverpool/the Irish News poll in March, 45% backed staying in the UK, 30% said they would vote for a united Ireland, and 25% did not express a preference or did not know. Previous polls have shown younger people are more likely to be in favour of a united Ireland. In recent weeks, political pressure over the cost of living crisis has forced Sinn Féin to pull its focus back on to more pressing issues for their voters. In the end, it may be the bread-and-butter issues that decide the question. “If a Sinn Féin first minister is perceived to perform well by crucial ‘persuadable’ voters,” says Pow, “then such voters may be more inclined to support a united Ireland in a future referendum.” But if a Sinn Féin first minister is perceived to perform badly, it could go the opposite way. A Sinn Féin win will be symbolic, Pow says, but “ultimately other factors will be more important when it comes to the likelihood of a united Ireland, such as people’s perceptions of how it would affect the economy and public services”. Data: Northern Irish voting data thanks to the ARK project, compiled by Nicholas Whyte. Notes: *Moderate nationalist party the SDLP came out on top in the 1998 assembly elections by first-preference votes, 0.7% ahead of the UUP, although because of vote transfers, ended up with fewer seats. The UUP’s David Trimble became first minister.