You know election season is under way in Northern Ireland when politicians are out beating the drum on the constitutional question.

Ahead of local elections on 2 May, parties have been unveiling their manifestos, but their rhetoric is not about bin collections and potholes. Instead, the parties are discussing (you guessed it) whether Northern Ireland should stay in the UK, or whether Ireland should be reunited.

Launching their campaign in the unlikely surroundings of unionist Ballymena on Monday, Sinn Féin’s leader Mary Lou McDonald said this election was “an opportunity for voters to say the time is up for Brexit and the time is up for DUP Tory cuts”.

But follow the party’s output on social media in recent days, and it’s clear the republican party is focused on the bigger picture. New logos, hashtags and campaign videos all send the same message: “A referendum on #IrishUnity is coming. Let’s win it.”

Irish unity is of course Sinn Féin’s raison d’etre, and will always feature in their electioneering. But in the political climate around Brexit, their desired border poll has never seemed a more likely prospect.

Britain Before Brexit: Northern Ireland Show all 12 1 /12 Britain Before Brexit: Northern Ireland Britain Before Brexit: Northern Ireland Derry, Londonderry A garage door displaying unionism, bolted shut, like a visual representation of Brexit Britain, locked to outsiders, safeguarding what’s inside Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Derry, Londonderry Rossville Street, the site of Bloody Sunday, where messages demand a severance with England. From this perspective, Britain is England in sheep’s clothing, the real empire, the centre of colonial power Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Bangor A political message in paint not yet dry, still forming, setting, adjusting, or in old paint finally eroding, melting away Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Bangor Moral judgement frames a residential view. The message seeks to make everybody involved in the religious narrative: those who don’t believe are those most in debt Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Castlerock The beach is sparse and almost empty, but covered in footprints. The shower is designed to wash off sand, and a mysterious border cuts a divide through the same sand Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Belfast Two attempts to affect and care for the body. One stimulated by vanity and social norms and narratives of beauty, the other by a need to keep warm in the winter night Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Belfast The gate to an unclaimed piece of land, where nothing is being built, where no project is in the making, where a sign demands the creation of something new Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Derry, Londonderry Under a motorway bridge a woman’s face stares, auburn and red-lipped, her skin tattooed with support for the IRA and a message of hostility to advocates of the Social Investment Fund Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Derry, Londonderry The Fountain Murals, where the curbs and the lampposts are painted the red, white, and blue of the Union Flag. A boy walks past in the same colours, fitting the scene, camouflaged Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Coleraine A public slandering by the football fields, for all to see or ignore. I wonder if it’s for the police or for the community Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Belfast A tattoo parlour, where the artist has downed tools, momentarily, bringing poise to the scene, which looks like a place of mourning, not a site of creation Richard Morgan/The Independent Britain Before Brexit: Northern Ireland Derry, Londonderry A barrier of grey protects the contents of this shop, guarding it from the streets outside, but it cannot conceal it completely, and the colours of lust and desire and temptation cut through Richard Morgan/The Independent

As Ireland continues to enjoy the firm support of Europe, the UK government is on its knees and its international standing is in tatters. A growing number of people in Northern Ireland are wondering if their interests might be better served in a united Ireland.

And, as the partition of Ireland has proven itself to be the single biggest obstacle to Brexit, its removal might not seem like a bad idea to many in Britain who want a clean break from the EU – something which is thwarted by a border of their own design.

All of this has left the DUP spooked. They tried to have their cake and eat it, despite being warned that pursuing Brexit would threaten the union. Now, with the union predictably threatened, the DUP are turning down the volume on Brexit and blaring some good old fashioned tribalism.

Launching their manifesto in east Belfast on Thursday, leader Arlene Foster called on unionists to vote for her party to show the strength of the union.

“Some claim it does not matter which party you vote for,” she said, “but you can be absolutely certain that it would be heralded as a massive success for republicans and a massive defeat for unionism if unionism was to be split and republicans were to have a massive win, and use the election results to strengthen their demand for a border poll.”

It’s a long way from 2013, when Foster was so sure of the union’s security, she suggested the DUP might back a border poll, to win it and put the issue to bed. She’s not so certain any more.

“We are living in profound political times,” she told the party faithful at the election launch, “and there can be no doubting in these times that every vote matters.”

But for the party that has been busy waving the Union Jack at Westminster, there are uncomfortable truths to face at home, where the union – with its political instability and economic uncertainty – is proving a harder sell than usual.

Of Ms Foster, unionist commentator Sophie Long tweeted, “Why is a border poll the worst thing she can imagine? What is the union delivering for working class people, single parents, for Irish speakers, for women and for gay people?”

Ultimately, the local elections won’t make much of a difference to the constitutional question – a border poll can only be called on the intuition of that most astute secretary of state Karen Bradley. But the results could serve as something of a litmus test.

More telling will be the results of the European Parliament elections on 23 May, in which Northern Ireland’s parties compete for three seats. The candidate list is still taking shape, but this is likely to become a proxy vote on Brexit, in a region that voted strongly for Remain, and where the prospect of a hard border is fiercely opposed.