This minor party holds the trump cards in the British Parliament. What is the DUP?

After last night’s shocking results, Britain’s Conservative Party had to make a deal with Northern Ireland’s Democratic Unionist Party (DUP) to return to government. It is not clear yet whether the Conservatives and DUP will form a coalition, in which both parties will jointly govern (perhaps with some Cabinet posts for the DUP), or whether the DUP will simply support the “minority government” from the outside, supporting the Conservatives on key votes but not being part of the Cabinet.

Most people outside British politics haven’t heard of the DUP, or if they have, don’t know much about it. Here’s what you need to know:

It is Northern Ireland’s hard-line Unionist party.

The DUP, as the name suggests, is a party that supports the union between Great Britain and Northern Ireland, and opposes nationalists and republicans who would prefer a united Ireland. In Northern Ireland’s political system, there is a very strong link between voting and religion: Most Catholics vote for nationalist or republicans; most Protestants vote for unionists. Since a peace agreement was reached a decade ago, Ulster politics have become more polarized, with Protestants tending to vote for more extreme unionists and Catholics voting for republicans, who were associated with the Irish Republican Army, instead of nationalists. This polarization benefited both the DUP, which took seats in Parliament from the less fervent Ulster Unionist Party in Thursday’s election, and the republican Sinn Fein party, which wiped out the nationalist SDLP.

It is associated with anti-Catholic evangelical Protestantism.

Originally, the DUP was closely associated with the Free Presbyterian Church of Ulster, which was founded by the Rev. Ian Paisley, who also led the DUP for decades. The Free Presbyterians are evangelical, fundamentalist Christians. In contrast to conservative evangelicals in the United States, who forged a tacit political alliance with conservative Catholics decades ago, the Free Presbyterians have strong anti-Catholic views. Paisley himself was involved with anti-Catholic paramilitaries in the 1960s and notoriously yelled that Pope John Paul II was the “Antichrist” when the pontiff visited the European Parliament in the 1980s. The relationship between the church and party has weakened over time: Paisley’s successor as party leader, Peter Robinson, started the movement away from domination by the Free Presbyterians, and the current DUP leader, Arlene Foster, is a member of the Episcopalian-linked Church of Ireland. Nonetheless, the party’s association with a particular brand of fundamentalist Christianity has shaped many of its political positions (including not only hostility to Catholic Irish nationalism, but to homosexuality too).

The DUP’s reemergence. 

After Paisley’s departure as party leader, the DUP had some difficult times. Robinson had been Paisley’s right-hand man for decades, but struggled to fill the shoes of his more charismatic predecessor, especially after becoming embroiled in a financial scandal involving his wife’s 19-year-old lover. Robinson’s successor, Foster, faced her own less salacious scandal involving a government incentive scheme that ended up costing vastly more than expected, leading to instability in Northern Ireland’s governing executive. However, the DUP did very well in Thursday’s election, not only nearly eliminating the rival Ulster Unionist Party, but also doing so by apparently attracting a surge of new voters. A cooperative relationship with the Conservative Party is likely to strengthen the DUP’s position.

The DUP and the Conservatives already had a relationship.

Before the election, the Conservatives had a majority in Parliament, but a narrow one. This meant that Theresa May, the Conservative leader, had good reason to cultivate a relationship with the DUP, to win its support and minimize the risk that defectors could undermine her government. May, therefore, devoted a lot of time and attention to the DUP. Now the DUP is in an even more advantageous bargaining position. We do not know the exact contours of the deal that it struck with May, but it is likely to be a good one for the Unionists. Northern Ireland’s economy depends heavily on public spending that is subsidized by the United Kingdom as a whole. It would not be surprising if it suddenly gets a lot more spending on infrastructure, which the DUP can then claim credit for. It is also likely that the DUP will use its privileged position to oppose social legislation (e.g. on gay rights and abortion) that extends to Northern Ireland.

DUP support might have implications for Brexit.

Northern Ireland has been put in a particularly tricky position by Britain’s decision to leave the European Union. Northern Ireland’s economy is linked both to the British economy and to that of the Republic of Ireland, which will remain a European Union member. Therefore, economic relationships would become far more complex if there were a “hard border” set between Northern Ireland and the Republic.

This situation could also have implications for the peace deal in the North, which was facilitated by the fact that both the United Kingdom and Ireland are member nations.

Northern Ireland’s republican party, Sinn Fein, wants Northern Ireland to have special status, which would lessen the impact of Brexit and perhaps dissociate Northern Ireland from the United Kingdom, making an eventual united Republic of Ireland a little more likely.

The DUP has demanded that there be no special status for Northern Ireland as part of its deal. It is not yet clear what this involves in practice — the U.K. and E.U. will have to reach some kind of accommodation on the Northern Ireland border — but the DUP clearly wants to have a veto over whatever arrangement is reached. The DUP will likely want some arrangement that minimizes the economic pain for supporters (such as farmers) who would be hurt by an overly restrictive border, but that also rules out the kinds of political institutions that could be used to destabilize Northern Ireland’s existing status in the U.K.

There may also be broader consequences for Brexit if the DUP deal with the Conservatives persists. The DUP has traditionally been strongly opposed to the E.U., which Paisley believed was a secret Catholic plot to dominate Europe.

The DUP campaigned in favor of Brexit. However, after last year’s referendum, the DUP made it clear that it wanted a ‘soft Brexit,’ with a fully worked deal with the E.U. on customs and trade. This will likely strengthen the hand of those Conservatives who want a mutually agreeable accommodation with the E.U, and weaken those who have threatened that they would prefer no deal to a ‘bad’ one.