The abortion referendum will not be decided until this day five weeks, May 25th, when voters go to the polling stations to cast their votes on the future of the Eighth Amendment.

A lot of campaigning has yet to come. But unless something very substantial changes in the campaign over the coming weeks, the proposal to repeal the amendment, and liberalise Ireland’s abortion laws, will be passed.

That is the clear message from today’s Irish Times/Ipsos MRBI opinion poll, our first since January and the first poll taken since the formal start of the campaign.

When undecideds and those who said they were unlikely to vote are excluded, the figures say 63 per cent will vote Yes, while 37 per cent will vote No.

Yes, the repeal vote has declined since January. Today 47 per cent of voters say they will vote for repeal; in January, that figure was 56 per cent. However, this looks more like a natural tightening of the campaign than a swing in momentum towards the retain side. We knew from previous polls that some of the repeal vote was “soft”, nursing significant doubts in particular about the proposal for the legalisation of abortion on request up to 12 weeks. So some slippage was probably to be expected. But it’s hard to see at this stage any decisive change in the central dynamic of the campaign.

In fact, support for the side favouring the retention of the Eighth Amendment also declined, albeit very slightly and within the margin of error, by one point since January. Crucially, the retain vote is not growing. The growth is in the numbers of voters who say they don’t know how they will vote yet.

Strip out the don’t knows, and those who are unlikely to vote, the numbers are stark: Yes: 63 per cent, No: 37 per cent. Whatever way you cut it, it’s a hefty lead.

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Strength of the repeal position

The entrails of the poll, and the accompanying questions, bear out the strength of the repeal position at this stage. A large majority of repeal voters say they are very committed to their position; 53 per cent say they would “absolutely never” change their minds, and 25 per cent say they are “extremely unlikely” to do so. That leaves 14 per cent who say they will “probably not” change their minds but are open to the arguments, and 7 per cent who say they “possibly could”.

These unsure Yes voters are the targets for the retain campaigners: their problem is they need to win an awful lot of them.

Today’s data also suggest that the undecided voters – which the No side needs to break almost entirely in its favour – are leaning towards Yes.

Voters also show a pretty high degree of knowledge about the Government’s proposals, with 85 per cent of respondents (and 90 per cent of Yes voters) saying they are aware of the proposals for abortion on request up to 12 weeks.

Long before the campaign began, we were talking about the importance of the middle ground as the place where the battle would be won or lost. So far, the repealers have been better at it. This is requiring some effort within the campaign, but it is paying off.

The anti-abortion campaigners, by contrast, have concentrated their efforts on energising their base. It may be expected that they will soon pivot to a softer message, more tailored to the middle ground – who want a change, but nurse doubts whether they want this change or not. There is some hope for them: 30 per cent of Yes voters say that the 12 weeks proposal goes too far. They are now target for the retainers.

Could the picture change?

Of course it could. The history of referendums in this country has often featured late swings and shock results. So a dramatic change in the course of the campaign is certainly possible. What we have to ask ourselves is how likely is it. The numbers and the history suggest it is not likely. Abortion as a subject of public policy is not like, say, Oireachtas inquiries. Or the Nice Treaty. People know what the subject involves. They will have thought about it before the decisive last fortnight.

Today’s poll suggests both a high degree of knowledge, and a reasonably firm commitment on the part of most voters to their existing positions. It is hard to see how the conditions for a late swing would manifest themselves.

Hard, but not impossible. People with a strong pro-life view, allied with those who have very serious reservations on the 12 weeks proposal, make a very significant minority of the electorate. There is a potential route to 50 per cent plus one for the campaign to keep the amendment; but it is a difficult one. The route to victory for the repealers is far more straightforward, and far more likely.