Although the main purpose of the June election is to decide the make-up of parliament, voters often use the occasion to send a message to their national governments.

From Italy to France, Austria to Belgium, Germany to the Netherlands and beyond, parties on the far right are eyeing significant gains. A Dutch exit poll has already placed Geert Wilders' Freedom Party almost neck and neck with a left-green alliance.

Polls suggest the two groups on the right, ECR and ID, could overtake the centre left and become the second largest force in Parliament. However, Germany's far-right AfD has been expelled from the ID group because of a series of scandals.

Until now the centre right has tended to work together with the centre left but the EPP may come under pressure to seek new allies if the centre left performs badly.

A move to the right could put the brakes on plans for new climate and sustainability laws and influence social or economic legislation. The EU's strong backing for financial and military aid for Ukraine could also be affected.