European Union (EU) officials are worried U.S. President Donald J. Trump’s visit to Poland will bolster the populist, right wing government there, encouraging their defiance of the EU, and damage “European unity”.

The president’s one-day stop-off – en route to the G20 summit in Hamburg – is for a gathering dubbed the Three Seas project, bringing together leaders from Central Europe, the Baltic States, and the Balkans.

The event has been convened by Poland as it bids to garner influence outside the EU – which has clashed with its nationalist government over migrant policy and sovereignty.

“One cannot but feel a bit suspicious if it isn’t an attempt to break up European unity,” an EU diplomat said about the Three Seas project, speaking to Reuters. Another senior EU official said it was part of Poland’s push towards “self-ghettoisation”.

Poland’s ruling Law and Justice (PiS) party and Mr. Trump have similar views on migration and climate change and share a suspicion of international bodies and globalisation.

The president also backed Brexit and predicted the further break-up of the EU; his dealings with the rebellious, right wing governments of Central Europe will be watched closely by Brussels.

Poland has taken a leading rolling in opening the rift between the ex-Communist, Eastern and Central EU nations (with largely right wing governments) and liberal Western European nations.

Most recently, Poland led a resistance to the EU’s forced migrant resettlement quotas – opposed by Romania, the Czech Republic, Slovakia, and Hungary – as the EU pushes to “sanction” nations that refuse to take thousands of Middle Eastern asylum seekers.

Polish Prime Minister Beata Szydło recently called the migrant quota policy “a madness of Brussels elites” in a speech in parliament.

“We encourage Mr. Trump to get out and travel as much as he can. He needs to understand Europe and he can do that by getting out and speaking to people, to European leaders,” said one European official, who declined to be named.

“[But] he can’t do deals with individual countries over the head of the European Union,” he added.

The president will be looking to push exports of U.S. gas on the trip as Poland attempts to reduce its reliance on Russia. Poland will seek reassurance of the president’s commitment to NATO as it faces a perceived threat from Russia.