The political systems of the central and eastern European countries that joined the EU in 2004 and 2007 have experienced instability since accession. Party systems have fragmented, with new populist and nationalist parties emerging and gaining support at the expense of the parties that led their countries into the EU. Coalition governments have been fragile and short-lived. This political instability represents an ongoing challenge and threatens democratic development, as citizens' trust in institutions has declined. The EU membership provides limited leverage to remedy domestic political issues.