Sinn Féin leader Mary Lou McDonald has appealed to the Government to support her party’s Bill to kick-start preparations for a Border poll on Irish unification.McDonald said she believed there was an “instinct” in Fine Gael to start preparing for a referendum, and it would be “astonishing” if Fianna Fáil, the republican party, voted against her party’s proposal.Under the Bill, the Government would be required to draft and publish a Green Paper on unification within 18 months, but McDonald indicated she would be open to discussing a different deadline if the Bill reached committee stage.The Green Paper would then inform an all-island citizens’ assembly, which would be set up to map out the costs, logistics and other practicalities of Irish unification. “This isn’t a Sinn Féin thing, this is a shared thing,” McDonald said. “But we can’t have more delay. More delay could prove counterproductive, it could prove dangerous. It’s in all of our interest to prepare.”[ Irish unity questions complicated by political instability in the UKOpens in new window ]Tánaiste Simon Harris had recently announced that Fine Gael was preparing a blueprint for Irish unification in advance of his party’s ardfheis in November. McDonald said recent debates between members of her party and Fine Gael politicians including Minister of State Neale Richmond had shown broad areas of agreement between the two parties on the need to start planning for a referendum.Singling out a recent media appearance by Richmond, McDonald said the Fine Gael TD was “extremely positive”, and “very clear” that the instinct and “understanding” within Fine Gael “is that this needs to happen”.She said it would be “kind of astonishing” if Fianna Fáil, the republican party, were to vote against the Bill, which will be introduced on Tuesday.[ Unity supporters must be prepared to make Northern Ireland work, says leading unionistOpens in new window ]Sinn Féin hosted a briefing in Leinster House on Tuesday to promote the Bill, which was attended by a number of cross-party TDs and Senators. Veteran Fianna Fáil TD Pat the Cope Gallagher told the meeting that, speaking in a personal capacity, he would be “anxious” the Sinn Féin Bill would pass and that Government TDs be offered a free vote on it. He added that he has been “loyal” to his party since he was elected in 1981, “and I’m hardly going to change now”.“But I will try to use my influence to ensure that we could move on, that we would have the Green Paper within 18 months or 24 months,” he said, adding the Bill was “quite simple and straightforward”.“So just to say that I’m doing my own bit, whether I’ve any influence or not,” he said. “But it doesn’t necessarily mean I’ll be voting with you, Mary Lou. If there’s a free vote, I’ll have no difficulty whatsoever.” Sinn Féin Senator Conor Murphy told the same meeting there was a “real prospect” of a Reform-led government coming to power in the UK. “Who can tell over the next number of years how that will play out? And in that scenario I think you could see, from this side of the Irish Sea, an unplanned-for referendum. And that’s why our position is that the Government should urgently begin engagement.”