The European Liberals last night (18 June) suffered an embarrassing setback after the N-VA, Belgium’s Flemish Separatist Party, voted to join the European Conservatives and Reformists (ECR) group in the European Parliament.

ALDE had opened the door for Belgium’s largest party to join them, despite the N-VA’s domestic rivalry with liberals in the group, by approving their membership before yesterday’s vote.

As things stand at the time of this article’s writing, the N-VA’s rejection of ALDE means the Eurosceptic and UK Conservative-led ECR, is now the third largest European Parliament group (more here). The N-VA’s four MEPs give the ECR 68 members, overtaking ALDE’s 67 parliamentarians.

>> Read: Cameron’s group challenges liberals as kingmakers in new Parliament

An N-VA party spokesman told Belgian media that more than 70 members voted to join the ECR, and more than 40 for the European Free Alliance, the N-VA’s former group. Just three members voted for ALDE, he said.

.@de_NVA party council chooses @ecrgroup, rejecting ALDE's open invitation to join. ECR overtakes ALDE to become third-largest group #ep2014 — Europe Decides (@EuropeDecides) June 18, 2014

Historically, the Liberals have held the “kingmaker” spot in the Parliament and on Tuesday night declared they were the third biggest parliamentary faction.

While negotiations are ongoing, the four seats represent a considerable coup at this stage in the group-forming process because the number of unattached MEPs is dwindling. There are also rumours of growing tension between Spanish nationalists and regionalists within ALDE, which could led to departures from the group.

Verhofstadt: ‘Not good’ for the EU that N-VA joins ‘Eurosceptic’ ECR

ALDE leader Guy Verhofstadt said, “We are reaching out to everybody who would like to help to reform and make the EU stronger […] that is why our group removed the obstacles to potentially allow the N-VA to join us.

“It’s obviously not good for the European Union that the biggest party in Belgium has chosen to join a very Eurosceptic, maybe even an anti-EU group, where there are several extreme right parties like The Finns party and the Danish People’s Party, as well as Alternative für Deutschland, who would like to leave the euro.”

ECR sources said they were pleased with the result. A vote on the N-VA’s membership by the ECR is to be held on Tuesday and is expected to go through without any problems.

A source said, “We share a eurorealist agenda with the N-VA and look forward to working with them as we build an EU that looks to the future.”

N-VA European party leader Johan Van Overtveldt said, “We have chosen the group where we get the greatest possible autonomy to freely determine our views and voting.

“We have negotiated with various groups and none are 100% in line with our thinking. But […] without a group you can not provide constructive political work in the European Parliament.”

Domestically, N-VA leader Bart de Wever is in negotiations to form a coalition government after his party’s victory in Belgium’s general election, which was held at the same time as the European elections. He is due to report on his progress to the King next week.

Nigel Farage’s Europe of Freedom and Democracy Group also announced last night it had the support it needed to form.

>> Read: Le Pen candidate joins Farage’s new EFD group

Partijraad N-VA besliste om in het Europees Parlement lid te worden van de ECR-fractie #ep #ecr — N-VA (@de_NVA) June 18, 2014

N-VA decision also leaves Basque and Catalan separatist parties in ALDE more isolated with UPyD and C's in, but no Flemish party #ep2014 — Europe Decides (@EuropeDecides) June 18, 2014