BELFAST, Northern Ireland — Northern Irish politics often feels far removed from debate on the British mainland, but this general election there is one big issue that spans the Irish Sea: Brexit.

Where British politicians on the campaign trail talk about the economy, tax and public services, debate in Northern Ireland has long been framed as much by its troubled past as by the concerns of the present — particularly around election time. Not in 2017. As in the rest of the U.K., its politics has been knocked sideways by the Brexit vote.

Voters here backed Remain by a margin of 56 percent to 44 percent, and there are extra concerns about what leaving the EU will mean for the border with the Republic of Ireland to the south.

The Brexit separation, however, maps onto older and more entrenched political divisions.

In Tigers Bay, a loyalist neighborhood of North Belfast, the gable end of a redbrick terraced house has “Vote Leave” scrawled on it in white letters. Across the street, red, white and blue union flags flutter in the breeze. Two minutes’ walk away, the color of the kerbstones has changed to green, and nationalist Sinn Féin posters warn of the threat from Brexit.

Here the scars of the three-decades-long Troubles are still all too visible. Around a sixth of the 3,500 people killed during the conflict died in North Belfast, and the violence has left a legacy of substance abuse, mental illness and corrugated iron "peace walls" separating Protestants and Catholics.

In March, after the Democratic Unionist-Sinn Féin power-sharing government collapsed over a botched renewable heating scheme, snap elections returned a unionist minority to the devolved parliament for the first time. If nationalists are to repeat that success in the general election they must win seats like North Belfast. And Brexit might be the key.

The constituency is a unionist heartland. The area has never returned a nationalist MP, and longtime Democratic Unionist Party MP Nigel Dodds — the party's deputy leader — is sitting on a majority of more than 5,000.

Dodds was firmly in favor of Brexit, even sitting as a director on the board of the official Leave campaign, while his constituents narrowly backed Remain by just a few hundred votes. And of North Belfast's five devolved assembly seats up for grabs in March, three went to nationalists — something that is giving them hope they can claim a prize scalp in the general election on June 8th.

“There is a sense that this time we can unseat a pro-Brexit MP. There is a broad coalition across the political divide. Nigel Dodds is incredibly popular inside his own core constituency but not outside of it,” said Martin McAuley, North Belfast candidate for the nationalist Social Democratic and Labour Party (SDLP).

Sinn Féin is certainly trying to reach beyond its core republican vote. In 2015, former IRA hunger striker Gerry Kelly finished second in North Belfast. This time around, the party’s candidate is John Finucane, a respected 38-year-old solicitor and son of a human rights lawyer murdered by loyalist paramilitaries acting in collusion with British intelligence in 1989. The killing was one of the most high-profile of the Troubles.

The legacy of the conflict remains unresolved almost two decades on from the Good Friday peace accord. “This isn’t an issue that is going away,” Finucane said. “If we don’t deal with it then it remains a poisonous sore at the heart of our politics.”

On the U.K.’s departure from the European Union, Finucane says there is "no clear plan for what Brexit means.”

Concerns about the economic impact of Brexit are growing on both sides of the 310-mile long Irish border. The Northern Irish economy is highly dependent on its southern neighbor, especially in food and drink, a sector that could be subject to high tariffs once the U.K. leaves the EU.

But, as with so much in Northern Ireland, Brexit increasingly plays into age-old political considerations. Republicans see special status as strengthening the connection with the Irish Republic. Unionists, meanwhile, are beginning to coalesce around leaving the EU. “Brexit has become orange and green,” said David Phinnemore, professor of politics at Queen’s University Belfast.

Ulster Unionist assembly member Steve Aiken, who backed Remain last year, says Northern Ireland needs to accept Brexit. “In the goldfish bowl that is Northern Ireland, there seems to be this presumption that the British people will have another vote (on the EU) and will stay. That’s not going to happen.”

Having sat on opposite sides of the Brexit debate, the Ulster Unionists (UUP) and the DUP recently agreed election pacts in a number of constituencies to keep out Sinn Féin. In North Belfast, the UUP is not putting up a candidate, in an effort to avoid splitting the unionist vote.

Unionists are hoping that March’s election acts as a “wake-up call,” said Dean McCullough, a 22-year-old DUP supporter from Tiger’s Bay. “People want unionist unity.” One of eight children, McCullough’s father worked in the famous Harland and Wolff shipyards before being laid off. The DUP will need to retain such working-class loyalist support in June.

Sitting MP Dodds declined to speak to POLITICO for this article but has said he is confident of winning. "I do not contemplate for a minute that Sinn Féin will win the seat," he told Belfast News Letter earlier this month.

That could depend heavily on turnout. Nationalists, who had grown increasingly disaffected with their traditional parties, voted in large numbers in March. Whether they will do so again is unclear.

“One of the questions is whether nationalism turns out in a British general election,” said Sam McBride, chief political correspondent at the Belfast News Letter. “Historically that hasn’t been the case."

“You are having negotiations to bring the parties together and now you have elections pushing them apart" — Neil Jarman, Institute for Conflict Research

There is an unmistakable sense of rage on the streets of Belfast — but not all of it is directed at Brexit and (locally unpopular) Theresa May. Northern Ireland is about to go into its fourth election in 18 months without a devolved government after talks stalled. With little prospect of a breakthrough, a period of direct rule from London seems inevitable.

“People are really tired of these elections. What is going on? Can’t they sort this out?” asked Callie Persic, a volunteer at Peas Park, a community garden sitting on an interface between nationalist and unionist communities in North Belfast. “It’s really disheartening.”

In nearby Alexandra Park, Andrew Doherty watches as his young boy plays on the swings. For decades, the park was divided by a 15-foot-high corrugated-iron wall separating loyalist and republican communities. There is now a gate in the “peace wall,” but Doherty said there is little sign of change. “I’ll not be voting,” he said. “They are all the same.”

A short walk away, in loyalist Tiger’s Bay, Katy Radford works on issues of social and cultural identity at the Institute for Conflict Research (ICR). “There is a general unhappiness at another vote,” she said. “I don’t think it’s an apathy, it’s a deep frustration.”

The absence of devolved government is already being felt. With no departmental budgets agreed, organizations such as the ICR have only been allocated funds for four months. Many fear for their future.

The Northern Irish general election narrative could hinge on North Belfast and places like it. If Dodds can hold on, unionism will almost certainly return more MPs than nationalism. On the other hand, a Sinn Féin victory would be hailed as further evidence of disquiet with Brexit and the British government’s failure to engage with Northern Ireland.

Few, however, expect the result to make a power-sharing deal between Sinn Féin and the DUP any easier. “This election is the worst possible thing to do,” said ICR director Neil Jarman. “You are having negotiations to bring the parties together and now you have elections pushing them apart. Nobody knows when, or how, to bring them back together.”