Brexit was also an issue. In the UK-wide referendum on EU membership on 23 June 2016, 56% of voters in Northern Ireland voted to "Remain" a member of the European Union while 44% voted to "Leave". The DUP supported the UK leaving the EU, while nationalist parties and most others opposed, fearing among other things the possibility of a hard border resulting with the Republic of Ireland. It became known during the campaign that the DUP spent £282,000 on a pro-Brexit advert in a newspaper that did not appear in Northern Ireland. The money came from the Constitutional Research Council, a minor pro-union group chaired by the former vice-chair of the Scottish Conservative Party Richard Cook.