The Irish political system may be about to undergo a major upheaval. Sinn Fein, a party that has traditionally been associated with the Irish Republican Army (IRA), has been doing increasingly well in the polls. Now, a new Irish Times poll finds that it is leading, with 25 percent of likely voters saying that they intend to vote for Sinn Fein. Fianna Fail is in second place with 23 percent, while Fine Gael, which is in government with the support of some independents (and the outside support of Fianna Fail, its historical rival) is third at 20 percent. This poll is likely to shock the Irish political system. It is still extremely unlikely that Sinn Fein will be the main party in the next Irish government, but its success may signal a realignment of it.

Ireland has had very stable politics — until now

Irish politics are difficult for outsiders to understand because the differences between parties often have less to do with the division between left and right than with historic splits. When Ireland gained its independence in 1922, it had to accept a deal with the British government that came with big qualifications. Most importantly, the six northern counties were left part of the United Kingdom, with a seemingly permanent majority of Unionists, who wanted to retain their Britishness. This led to a brief but very bitter civil war among the rebels who had fought for Irish independence. The winning side — which wanted to accept the deal with Britain — became Fine Gael. Some of the losers effectively accepted their loss and reentered Irish party politics in the late 1920s, becoming Fianna Fail. Others wanted to continue the “armed struggle” against the British. This was the modern origin of Sinn Fein.

From the 1920s on, Irish politics was dominated by the fight between Fianna Fail and Fine Gael (whose original name was Cumann na nGaedheal), with the small left-of-center Labour Party sometimes acting as a coalition partner, and other smaller parties entering and leaving the stage. Sinn Fein was excluded.

In part, this was by choice. Sinn Fein did not recognize the legitimacy of the Irish state and instead effectively owed its allegiance to the IRA Army Council. Indeed, for long periods, it was difficult to distinguish Sinn Fein from the IRA: Sinn Fein leader Martin McGuinness had served in the IRA leadership, and Gerry Adams had long been thought to be an IRA member, though he denies it. In part, this was because Sinn Fein was perceived as a subversive organization, and excluded from Irish politics. TV and radio stations were forbidden from broadcasting programs with Sinn Fein members until 1993.

Now things may be changing

The Irish political system has changed, and so, too, has Sinn Fein. The economic crisis of 2007-2009 hit Ireland particularly hard, but its main political result was to hand over control of government from Fianna Fail to Fine Gael. However, it has been clear that many voters were unhappy with the main parties on offer. Smaller groupings on the left have made significant gains in recent elections. Sinn Fein has also made efforts to soften its image and to emphasize left-wing politics rather than military struggle. Its current leader has no direct connection to the IRA.

Over the past two years, the Fine Gael government’s main concern has been to manage the economic and political fallout from Brexit. It is generally perceived as having done that well. However, now that Brexit is fading from the headlines, it is finding that voters are worried about more everyday issues, such as problems with housing and health care, and ready to punish it for its perceived failings. This has benefited Fine Gael’s main rival, Fianna Fail, which has traditionally seen itself as the natural party of government, but which suffered shattering losses in popularity after the financial crisis. It has benefited Sinn Fein even more. Fianna Fail was closely aligned with the government, which it effectively supported, allowing Sinn Fein to remake itself as the voice of opposition. Now, Sinn Fein is reaping the benefits.

Sinn Fein is unlikely to be in government — yet

Even though Sinn Fein is ahead in the polls, it is extremely unlikely to be the main party of government. First of all, it is probably not running enough candidates. Second, it may suffer under Ireland’s complex electoral system, which allows voters not only to vote for their preferred candidates, but also to express second, third, fourth and fifth preferences, which may come into play as the count continues. Sinn Fein is still a highly divisive party, and it is possible that the supporters of other parties will be less likely to give it their preferences. Finally, other parties do not want to work together with Sinn Fein. Fine Gael is viscerally opposed to a party that it perceives as still organically linked to the IRA. Fianna Fail’s leader also does not want to work together with Sinn Fein, in part because of principle, and in part because Sinn Fein might eat Fianna Fail’s electoral base if it is perceived as a legitimate party of government.

So the most likely outcome is one where Sinn Fein is not in government, but where it will be a very large opposition party, and perhaps the largest. This is likely a comfortable outcome for Sinn Fein, too, allowing it to criticize government policy and grow its base of support. It will be a sufficient victory for Sinn Fein if it becomes a major political party, which has to be accommodated by other parties and the Irish political and broadcasting establishment, rather than reviled or ignored.