Sinn Fein and lots of (other!) marginal groups financed by anti-EU groups from outside the country. Anti-abortion people claiming that the EU is going to force abortion on the country, pro-neutrality people recycling their claims about us being forced into NATO (as if that would make one blind bit of difference to the government's kowtowing to Washington) and so-on. The  media will magnify their voices in the name of balance and they'll be unconstrained by little details like the truth as per usual.  

What fun it will all be.

Apparently Merkel and others will be coming to help out Bertie and the lads persuade us.