Dr David Shiels is a Policy Analyst at Open Europe and also works on contemporary political history.

The political parties in Northern Ireland have been launching their campaigns for the European elections this week as the region prepares to go to the polls again on 23 May.

With three seats available to Northern Ireland as a single constituency, representation in the European Parliament has always been highly prized. Having an MEP elected gives the parties an international profile. After topping the poll in the first direct elections in 1979, Rev. Ian Paisley, the founder of the Democratic Unionist Party (DUP), declared that he was now the “leader of Ulster.”

For Sinn Fein, who claimed the top spot in 2009, winning a seat at the European level confirmed their position as the dominant Nationalist party while enhancing their ‘all-Ireland’ credentials. The European Parliament is an important alternative to Westminster, where Sinn Fein MPs abstain from taking their seats.

Eleven candidates are contesting these elections, including candidates from the five “main” parties currently represented in the Stormont Assembly, several smaller parties, and independents. Unlike in Great Britain, the European elections in Northern Ireland take place using Single Transferable Vote (STV), with voters ranking candidates in order of preference. Two sitting MEPs are defending their seats – Sinn Fein’s Martina Anderson and the DUP’s Diane Dodds – while Jim Nicholson, the incumbent Ulster Unionist Party (UUP) MEP, is standing down.

A recent Lucid Talk poll for The Times put Sinn Fein in the lead with 24.6% of first preference votes, followed by the DUP on 18.2%. With these two parties likely to retain the first and second seats, there is expected to be intense competition for the third seat.

As in all elections in Northern Ireland, the results will be scrutinised for what they say about the balance between Unionism and Nationalism. The election will also be a test of opinion on Brexit and the backstop. As Sinn Fein puts it, the elections are “an opportunity to send a message loud and clear that the people of the north reject Brexit.” Victory in the third seat for an anti-Brexit candidate would be a symbolic defeat for Unionism at a time when all the Unionist parties are campaigning to respect the result of the referendum.

In 2014, the Unionists won just over 50% of the first preference votes – 52.6% if the votes of UKIP, the Conservatives and the now-defunct NI21 party are taken into account – but if their share falls significantly below 50% it could lead to renewed calls for a border poll.

Partly because the stakes are so high, the internal battle for votes and preferences will be fierce. With greater competition on the Unionist side, the DUP will need to demonstrate that its Brexit stance retains the confidence of the Unionist electorate. Part of their strategy will be to appeal to Northern Ireland’s Leave voters.

Following her confirmation as the party’s candidate, the MEP Diane Dodds described the election as “an opportunity for those who want the 2016 referendum result to be respected to ‘tell them again’.” The party’s campaign will be pushed in a pro-Brexit direction by the electoral challenge from Jim Allister, a staunch Brexiteer whose slogan is “out means out.” The TUV leader is himself a former DUP MEP who left the party in protest at its decision to enter power-sharing with Sinn Fein.

All of this creates problems for the UUP, which must compete for votes and transfers from pro-Brexit Unionists, while also trying to appeal to pro-Remain opinion. The UUP candidate, Danny Kennedy, was a Remain voter who appears to be pitching himself as a pragmatic candidate, highlighting that he is a border Unionist and opposes a No Deal Brexit. That said, the party may struggle to get this message across when competing voices are more emphatically pro-Brexit or pro-Remain.

On the Remain side of the debate, there are the two main Nationalist parties, Sinn Fein and the SDLP, as well as the Alliance Party, the Greens and two independents. Colum Eastwood, the SDLP leader, is hoping to “take back John Hume’s seat,” a message reminding voters of the party’s strong history of pro-Europeanism – Hume being the former party leader and long-term MEP. As with the UUP on the Unionist side, the SDLP has struggled with its message in recent years, but the party’s strong anti-Brexit message may give it a clearer mission in this election.

Meanwhile, the Alliance Party is also thought to be in with a good chance at taking the third seat. The party’s performance in the recent local elections has given it some momentum and its candidate (and party leader) Naomi Long is thought to be particularly ‘transfer friendly’ – someone who can attract second and third preferences from Nationalist voters in a way that the UUP cannot. With the Unionist parties focused on the existential nature of the Brexit question, Long stresses that opposition to Brexit – or support for the backstop – does not necessarily equate to opposition to the Union with Great Britain.

Significantly, the fact that Sinn Fein has urged its supporters to give their second and further preferences to other Remain parties lends some credibility to her efforts to move beyond the ‘green and orange’ labels traditionally associated with Northern Ireland politics.

Finally, the performance of the smaller parties and the two independent candidates may well make a difference, especially in an election when first preference tallies as well as transfers are important. The Conservative candidate will struggle to get a hearing but he may take some first preferences from Unionist parties, and UKIP are also fielding a candidate (UKIP did better than the Conservatives last time around). Meanwhile the Greens, who enjoyed success at the local elections recently, will be using the European poll as a means of establishing a stronger support base across both communities.

What does all this mean for Brexit and for Northern Ireland? In the end, the results of the European elections will have to be treated with caution. As in the rest of the UK, voters may use the election to register a protest against the establishment parties. The elections are also taking place when talks are ongoing to restore the power-sharing Executive. It is possible that the Remain majority in Northern Ireland could assert itself, but the Unionist parties could equally become entrenched in their pro-Brexit / anti-backstop message.

A good election for the DUP may not be good for Unionism. Decline in support for either the DUP or Sinn Fein may be masked by the result in the third seat. Ultimately, the elections may reveal less about Brexit and more about the longer-term trends in Northern Ireland’s political landscape.