UK Prime Minister David Cameron's Conservative party is torn between those standing by their leader and support his EU membership renegotiation deal and those who are defying him and urging British voters to vote to leave the Union.
So, out of the European Parliament's 21 Conservative MEPs, which ones are campaigning to put themselves out of a job, and which aren't quite yet ready to leave Brussels?
To date, the majority of them (10) are on Cameron's side, telling their constituents that the UK should remain a member of the EU. Those supporting the various 'in' campaigns are:
Richard Ashworth
Vicky Ford
Jacqueline Foster
Ashley Fox
Julie Girling
Sajjad Karim
Timothy Kirkhope
Anthea McIntyre
Kay Swinburne
Charles Tannock
Meanwhile, six Conservative MEPs have revealed they want the UK to leave:
Amjad Bashir
David Campbell Bannerman
Dan Hannan
Andrew Lewer
Emma McClarkin
Syed Kamall
Four MEPs have not as yet announced which side they will be rooting for, meaning Cameron cannot guarantee majority support from his Brussels party members:
Dan Dalton
Ian Duncan
James Nicholson
Geoffrey Van Orden
UPDATE: According to parliamentary sources, Nirj Deva will not be campaigning for either side.
UPDATE: Here is an outline of Conservative MEPs' voting intentions so far:
Within other parliamentary groups, MEPs in the S&D, ALDE, GUE/NGL and Greens/EFAs group support membership. However, those in the notoriously eurosceptic EFDD and ENF groups unsurprisingly do not.
This article will be updated as more information comes in.