The Irish Unity Debate in the United States: The Limits of American Leverage

By Mary C. Murphy, 

Ten years after the Brexit referendum, the fallout from that decision continues to reverberate. Across the island of Ireland, the period since 2016 has seen a quantitative and qualitative increase in discussion and consideration of constitutional change, although some of the energy around the issue has episodically waxed and waned. Public opinion polling on the prospect of a united Ireland shows some subtle evidence of growing support in both Northern Ireland and the Republic of Ireland. The volume of academic work, thinktank papers and policy reports considering North-South linkages and themes related to constitutional change has multiplied. Pro-Irish unity civic society organisations such as Ireland’s Future have emerged and are proactively advocating for a border poll. Media coverage of issues connected to the constitutional question has increased in volume. 

In the United States, groups like the Ancient Order of Hibernians (AOH), the Irish National Caucus and many others have long been advocates for the achievement of a united Ireland. In the post-Brexit period, other political actors have begun to strategically and more robustly mobilise in the US with Sinn Féin to the forefront in promoting its pro-Irish unity messaging there. In Sinn Féin’s case, this has involved extensive networking, convening of deliberative events, hosting information webinars, producing regular publications and engaging in media outreach. The party has cultivated relations with key Irish-American politicians and organisations with the aim of mobilising an informed constituency in the US which will advocate for a border poll and strengthen calls for the achievement of a united Ireland. 

Sinn Féin sees it as politically important for the party to be active in North America. Its approach is focused on ensuring that the British government, as per the provisions of the 1998 Agreement, is held accountable in terms of the calling and timing of any future border poll. The party views the US as an ally and a bulwark against British government action (or inaction) when it comes to calling a referendum on Irish unity. 

But to what extent is US interest consequential for Irish nationalism in its efforts to advance constitutional change? It is commonly agreed that Irish-American mobilisation was politically significant and impactful during the Northern Ireland peace process in the 1990s, and in the context of recent opposition to Brexit. Notably, in both cases, Irish-America’s appeals were aided by the fact that they did not clash with core US interests, rather they dovetailed with support for peace in Northern Ireland and for the protection of the 1998 Belfast/Good Friday Agreement. 

Outside of these periods of intense US activism, diaspora groups, and Sinn Féin in particular, see the US as being similarly instrumental in relation to the pursuit of Irish unity. According to Friends of Sinn Féin USA: ‘There would have been no Good Friday Agreement without the US. There will be no Irish unity without the US’. 

To what extent is this assessment valid? Unlike Sinn Féin, neither the SNP nor Plaid Cymru have expended much effort at a party level in cultivating their respective diaspora communities on the constitutional question. There are likely pragmatic and financial reasons for that, but it is also worth querying the utility of Irish, Scottish and Welsh nationalists seeking to influence the US on the question of possible UK constitutional change.

In 2014, in response to a media question about the upcoming Scottish independence referendum, President Barack Obama expressed hope that the UK, as one of the US’ closest allies, would remain ‘strong, robust, united’. This was widely interpreted as a pro-union position and may have been influenced by the impact of constitutional change on US security interests linked to NATO, intelligence-sharing and nuclear facilities. (Of course, quite what impact the President’s position and preference had on the choice made by Scottish voters is unclear). 

Ten years since the Brexit vote, the prospect of UK constitutional upheaval resulting in a dis-United Kingdom – particularly at a time of international geopolitical instability – does not align closely with core US strategic national interests. In this context, the basis for President Obama’s 2014 pro-union position has not materially changed. 

Moreover, since the 1970s, the US has generally aligned its approach to Northern Ireland with that of the British and Irish governments, with Brexit being a notable exception. There is little reason to expect a future US administration to deviate from this pattern, particularly on an issue as contested as constitutional change. US restraint may be further shaped by the declining electoral salience of an Irish‑American voting bloc that is now more diverse, diffuse and politically heterogeneous than in previous generations.

So is international mobilisation on the constitutional question worthwhile? Successful international lobbying in the US is most effective when it reinforces existing US strategic preferences, not when it asks the US to challenge them. When goals diverge from core US priorities, influence diminishes – a pattern widely documented in the academic literature on ethnic lobbying and foreign policy. All of this means that even a strong and mobilised movement may struggle to persuade a US administration to lend its weight to calls for Irish unity. 

In their efforts to secure constitutional change, nationalist parties across the UK may be better advised, as detailed by McEvoy, Todd and Deane in their contribution to this blog series, to focus their attention and resources on influencing domestic politics and grassroots communities. The centre of gravity remains at home: in domestic politics, in public opinion, and in the everyday work of persuading voters who may be disengaged, undecided or sceptical.

And none of this is to say that diaspora mobilisation is without impact. There is certainly merit, for those who seek constitutional change, in cultivating support in the US (and elsewhere). But the greater impact of international mobilisation is likely to be seen in the period after constitutional change when the political, diplomatic, economic, symbolic and moral support of other countries and diaspora communities may be instrumental in easing the constitutional transition. 

International mobilisation can amplify, support and encourage, but it is unwise to assume that it will be decisively important in terms of influencing the timing, process and outcome of UK constitutional change. 

Mary C. Murphy is Professor of Political Science and Director of the Irish Institute at Boston College.