Croatia is using the Brexit talks to try to open the U.K. to its workers.

Senior Croatian officials, including Prime Minister Andrej Plenković, have asked the EU’s top Brexit negotiator to ensure that Croats can live and work in Britain starting next July and thereby benefit from any deal on the rights of EU citizens in the U.K. once it leaves the bloc in 2019.

Unlike citizens from the other 26 remaining EU states, Croats do not have an automatic right to live and work in the U.K. because of temporary restrictions imposed after the Central European state joined the EU in 2013. The restrictions, which currently run until June 30, 2018, can be extended by London for another two years. If that happens, as expected, then Croats would not be able to benefit potentially from Prime Minister Theresa May’s offer of “settled status” in the U.K. after Brexit.

“Rights of citizens is an especially important area for Croatia, bearing in mind our specific position in relation to freedom of movement for workers,” Maja Bogdan, deputy foreign policy adviser to Plenković, told POLITICO.

The fate of Croatian workers was a major topic when the EU’s Brexit negotiator, Michel Barnier, visited Zagreb last fall — a visit made famous when he tweeted a photo of himself outside the city’s Museum of Broken Relationships. But the issue has been raised repeatedly in Brexit consultations since then, officials said.

The Croatian démarche, for now limited to diplomatic conversations behind closed doors, is an early signal that specific priorities of individual countries are bound to emerge during the talks — possibly complicating, if not derailing, a deal on the U.K.’s orderly withdrawal. It also suggests that the vaunted cohesion shown so far by the 27 remaining members of the EU may not last.

On paper, Croatia cannot block a deal with the U.K. over the issue, as only a so-called qualified majority of EU countries are required for approval of an agreement, according to Article 50 of the EU treaties.

So far, Zagreb has not threatened anything of the sort, EU and Croatian officials said. But disunity among the 27 could carry a political price for the EU, and may give London an opening to exploit this or other divisions that could bubble up in the next year-plus of negotiations.

Barnier has insisted that any Brexit accord should treat all EU citizens equally. “There must be equal treatment between all EU and U.K. nationals in the U.K.,” Barnier said in a speech in Florence in May, “Inversely, equal treatment between U.K. citizens and the nationals of the 27 member states must also be the rule when U.K. citizens live in those 27 states.”

But Croatian officials, including Plenković, have told Barnier that it is impossible to claim such equal treatment unless London agrees to lift the restrictions on Croatian workers, which the U.K. can legally extend until July 2020. That is more than a year after the end of the two-year Article 50 process when Britain is expected to formally leave the bloc.

“In order for our citizens to have the same rights as other EU citizens, it is imperative for the U.K. not to extend the transitional period,” Bogdan said. “That way, our citizens would be able to attain ‘settled status.'”

Nataša Owens, the president of European Movement Croatia, a pro-EU nonprofit group, said that Croatians were at risk of losing out.

“As we were the last country to join the EU before Brexit and as we are still under the restrictions,” Owens said, “we might might find ourselves in the unique and undesirable position of our citizens having a different status than all other member states. We require clarification.”

She added, “While the number of Croatian citizens who work in the U.K. is not significant [about 4,000, according to the U.K. Office for National Statistics], we would want to avoid being in a disadvantageous position.”

Owens said she recognized that Croatia was asking for special consideration. “EU strategy is to negotiate as a block with the U.K. but all members thoughts and concerns are constantly canvassed,” she said.

Under the EU treaties, restrictions on the freedom of movement of citizens of new EU states are permitted for up to seven years if a country anticipates a “serious disturbance” in its labor market.

The U.K. imposed such restrictions on Romania and Bulgaria after they joined the EU in 2007, for the full seven years allowed under the EU treaties. And while London has not signaled its intentions, officials in Brussels and Zagreb said they expected the U.K. would seek to keep the restrictions for Croatia in place as long as possible.

EU rules require the U.K. to notify the Commission if it intends to extend the restrictions on Croatian workers, but officials said Brussels cannot stop London from prolonging the ban.

The EU and the U.K. have each said they want any withdrawal agreement to protect the rights of EU citizens who live in the U.K., and U.K. citizens living in the EU27 — as of the U.K.’s withdrawal date.

Croatia’s position is that an extension of the restrictions to 2020 would effectively turn the temporary measure into a lifetime ban, though the U.K. could adjust its future immigration policy at any time.

European Commission officials said that Barnier and his negotiating team were aware of the importance of the issue to Croatia, but declined to comment further.

“The Commission is well aware of this particular situation,” an official said. “This is something we are also discussing as part of the discussions with the 27 and we will work closely with the Croatian government.”

The first full-round of Brexit negotiations last week ended with the sides still deadlocked on all of the core divorce issues, including citizens’ rights.

Until now, EU officials have tried to limit discussion of individual needs to two particularly unusual cases: the border situation between Ireland and Northern Ireland, and the special status of Gibraltar, an issue of contention between the U.K. and Spain.

But there are numerous other priorities that individual countries could start to push, as negotiators begin to delve into nitty-gritty details, such as the concerns in the Netherlands over protections for dockworkers, or the status of U.K. military bases in Cyprus.

Equal treatment

Ironically, it was the absence of such restrictions on workers after Poland and other Central European states joined the EU during Tony Blair’s government in 2004 that led to a huge influx of immigrant workers into the U.K. Some analysts say the backlash against that wave of immigrants served to galvanize the British movement to leave the EU.

Bogdan, the Croatian foreign policy adviser, said officials in Zagreb had faith that Barnier would uphold the principle of equal treatment for the EU27. “We are confident,” she said.

Ireland, which has by far the most complex issues at stake in the early stage of Brexit negotiations, has expressed support for resolving Croatia’s concerns. Irish officials are eager to maintain unity among the EU27, so as not to endanger efforts to secure a special border regime and safeguards for the Good Friday Agreement, as part of any Brexit accord.