Now is not the time to expand the 28-nation European Union by admitting new member states because there is too much to sort out within the bloc, Luxembourg Prime Minister Xavier Bettel said on Friday.

Luxembourg in 1957 was one of six founding members of what is now the EU. It expanded in 1973 and took in mostly central and eastern European states in 2004 and 2007. Croatia became the most recent country to join, in 2013.

The Union will go down to 27 nations in March, 2019 when the UK leaves after two years of negotiating the terms of its withdrawal, known as Brexit.

“If you ask me, clearly, if Europe should get new members tomorrow, no,” Bettel told reporters before a summit in Brussels. “Maybe the day after tomorrow but not tomorrow.”

He cited the need to “resolve problems” within the EU and Brexit.

Bettel was speaking at a meeting of heads of states and government from the EU and its six eastern partner countries; Armenia, Azerbaijan, Belarus, Georgia, Moldova and Ukraine. Talks are based around building on four priority areas agreed on at the last summit at the Latvian capital Riga in 2015; economy, governance, connectivity and society.