The First Ministers of Scotland, Wales and Northern Ireland will demand in Cardiff the right to hold referendums on independence from Great Britain

The leaders of Scotland, Wales and Northern Ireland are meeting in Cardiff for an unprecedented summit, where they are expected to sign a joint declaration on the right to self-determination and the holding of independence referendums. The meeting comes after British Prime Minister Andy Burnham suggested he could authorize a new referendum in Scotland if there were clear consensus in favor of it.

Leaders John Swinney and Rhun ap Iorwerth, along with a representative of the Northern Irish administration, will also sign a memorandum on cooperation in the economy, energy, relations with Europe and self-determination. Mary Lou McDonald, leader of Sinn Féin, will also attend the meeting.

For the first time, pro-independence parties lead all three nations with devolved administrations: the SNP in Scotland, Plaid Cymru in Wales and Sinn Féin in Northern Ireland. Swinney argues that the situation points to the need for major constitutional changes and warns of a possible “post-United Kingdom future.”

The summit comes after Donald Trump’s statements in favor of a united Ireland. Burnham has ruled out holding a Scottish referendum before the next parliamentary elections, however, and said there is currently no clear consensus for such a vote.