Support in Northern Ireland for a united Ireland has fallen to a 10-year low, according to new polling. The Institute of Irish Studies at the University of Liverpool found that 35.8% of respondents would support unification, down nearly five percentage points from 40.6% in 2025.

Over the past decade, support for a united Ireland had been steadily increasing. In 2017, the figure was 35%, rising to 38% by 2023 and 41.8% in 2024. However, the most recent statistics suggest the trend may be reversing.

Support for remaining in the UK has also steadily increased. The polling from the Institute of Irish Studies this year found that 61.4% of respondents would vote to remain in the UK, compared to 59.4% in 2025.

The findings come as Sinn Féin has continued to strengthen electorally in recent years. In early 2024, the party’s Michelle O’Neill became the first ever nationalist first minister of Northern Ireland. After entering office, she suggested that there would be a unification referendum within a decade. At the 2024 general election, Sinn Féin became the largest of Northern Ireland’s parties at Westminster.

In 2023, while Leader of the Opposition, Keir Starmer downplayed the idea of a referendum on a united Ireland. He suggested that a vote on unity was “not even on the horizon”, and that the idea was “absolutely hypothetical”.  Shortly after he was elected, Starmer stated that he was committed to the Good Friday Agreement. Former Labour leader and current independent MP Jeremy Corbyn has been a consistent supporter of a united Ireland, as has former shadow chancellor John McDonnell.

This latest data from the Institute of Irish Studies goes against the trends recorded by other pollsters. The Northern Ireland Life and Times Survey suggests that support for Irish unification has been increasing since 2015. Meanwhile, polling from the Arins Project backs this up, suggesting that support for Irish unity had been increasing in Northern Ireland but remained far lower than support for staying in the UK. Further polling suggests 66% of respondents from the Republic of Ireland would support a united Ireland.

Ireland became a largely self-governing state in 1922 as a result of the Anglo-Irish treaty, after a series of conflicts between Irish Republicans and the British state, including the Irish War of Independence. This established the Irish Free State in the south and Northern Ireland in the north as a separate region of the UK. The Irish Free State later became the Republic of Ireland after a formal declaration of independence in 1949.

The Good Friday Agreement provides for a referendum if it appears that a majority would support Irish unification. The Agreement was signed in 1998 between the UK and Irish governments and eight Northern Irish political parties, with the Democratic Unionist Party refusing to participate. This came after decades of fighting between the unionists and republicans, known as the Troubles. The Good Friday Agreement built on earlier ceasefires by paramilitary organizations and established power-sharing between unionist and nationalist parties in Northern Ireland.