Sinn Féin held all seven of its Westminster seats at the 2024 general election, and for the first time was the largest Northern Ireland party in the House of Commons, as well as at Stormont since 2022 and in local government since 2023. Michelle O'Neill had been sworn in as First Minister on 3 February 2024, the first Irish nationalist to hold the office, with the DUP's Emma Little-Pengelly as deputy First Minister, and the Executive has run continuously since. No other party on the island holds first place at Westminster, Stormont and in local government at the same time.
The seven MPs, though, do not take their seats. They will not swear the oath of allegiance required to sit, forgo the £91,346 salary, and claim only the office and staffing expenses allowed to non-sitting members under a 1933 Commons resolution. The consequence is that the Windsor Framework, Troubles legacy legislation, welfare changes and the decisions that set Northern Ireland's block grant are all taken in a chamber Sinn Féin chooses not to enter; the party recorded no votes and no speeches at Westminster on any of them. Abstentionism is a decades-old principle, argued on its own terms, and its practical price is that every reserved matter affecting Northern Ireland is settled by the parties that turn up.
The constitutional payoff the institutional success was meant to bring has not materialised. The 2024 manifesto asked the British and Irish governments to set a date for an Irish unity referendum by 2030, with a citizens' assembly and a joint Oireachtas committee to plan the transition. Mary Lou McDonald has kept up the demand, calling Taoiseach Micheál Martin the "biggest barrier" to unity, but the British government's position is unchanged: a border poll will be called only when a majority looks likely to vote for reunification, and Sinn Féin has not produced evidence that it would. Polling has moved around without showing a settled nationalist majority, and the combined unionist vote at Westminster remained slightly larger than the nationalist one.
The Republic made the strategy harder. At the Irish general election of November 2024, Sinn Féin came second, winning 39 of the 174 Dáil seats, and returned to opposition as Fianna Fáil and Fine Gael formed a government with independents. Its first-preference vote fell by about five and a half points, from the 24.5 per cent that had made it the largest party in 2020 to roughly 19 per cent. The all-island momentum the manifesto assumed, a party strong enough on both sides of the border to press both governments toward a referendum, now runs one way: Sinn Féin leads in the North and sits in opposition, diminished, in the South.
On devolved matters the record is its own to defend. Health is run from Stormont, and waiting times, A&E performance and staffing were among the dominant Northern Irish questions through 2025 and 2026, on a file Sinn Féin controls. Its central Westminster welfare demand, scrapping the two-child benefit cap, was met in November 2025 by the Labour Budget, delivered from the Commons the party will not sit in.
Where the party has invested, it has grown. In Fermanagh and South Tyrone it stood Pat Cullen, the former head of the Royal College of Nursing, and turned a majority of 57 into one of 4,571. But the founding purpose, a united Ireland, depends on a referendum neither government has agreed to hold, and the 2024 results left Sinn Féin leading in the one jurisdiction whose parliament cannot call that vote while abstaining from the one that can. The next test is whether it can convert its lead at Stormont and in local government into the cross-border weight a border poll would require, or whether that lead has reached its constitutional ceiling.