Leo Varadkar (Dublin West, Fine Gael) | Oireachtas source

There was a memo before the Cabinet on the issue today. We agreed that we would proceed with a referendum to extend voting rights to all citizens, no matter where they lived, be it Northern Ireland or other parts of the world.

It will not only be passport holders. It will be all citizens because some citizens do not have a passport or cannot afford one or perhaps cannot travel. We have taken the decision that this referendum could be contentious. It will involve a good deal of planning, it needs a good campaign and we want to win it. Given the uncertainty around Brexit at the moment and the fact that we have local and European elections and other referenda on 24 May, we want to have it in October instead to give us more time to prepare the ground and inform people. This will give us a better chance, I believe, of getting it passed. Of course the next presidential election is not scheduled until 2025, so we have a good deal of time yet to get it done. The commitment is to do it in the last week of October.

See this speech in context