Wicklow
DL's Ms Liz McManus retained her seat last year but had fewer than 400 votes to spare over Labour veteran Mr Liam Kavanagh, who is keen to have a go at regaining the seat he had held since 1969. The Labour vote was divided last time, with new Bray-based candidate Dr Tim Collins winning almost 2,000 votes but transferring poorly to Mr Kavanagh. Mr Kavanagh's supporters believe he would have won had he been the sole candidate.
Were Ms McManus to be a candidate of the Labour Party or a new "formation" she would undoubtedly gain some Labour votes, which would very likely put her ahead of Mr Kavanagh. He would then be reliant on a significant surge of Labour support in order for him to be elected.
This problem could be resolved if Mr Kavanagh runs and wins in Leinster in next year's European elections. Otherwise, a lively general election is in prospect in Wicklow, preceded by an even livelier selection convention.
Dublin North West
Home of Democratic Left leader Mr Proinsias De Rossa and tough Labour campaigner Ms Rois in Shortall. Through a long, long count in 1997 a loss by one or other was considered inevitable. However, both scraped home in the end, with Fine Gael's Ms Mary Flaherty losing out instead.
But then there were four seats. Now the constituency has been reduced to three and one of the left seats must almost certainly go. On a united ticket, Mr De Rossa would probably retain his own vote while gaining some from the new formation. Ms Shortall is highly vulnerable.
Some wishful thinkers say the problem would be solved if Mr De Rossa ran for the European Parliament, to which he was elected before. However Ms Bernie Malone MEP has already got herself selected to contest the poll next year. And you know what happened to the last person who tried to land on Ms Malone's ticket . . .
Dun Laoghaire
The scene of a high-profile Labour casualty last year when the then minister for education, Ms Niamh Bhreathnach, lost her Dail seat. Democratic Left's Mr Eamon Gilmore comfortably held on to his. However, the combined vote of the two parties is well short of what would be needed to win two seats. Activists in both parties believe that the chances of Mr Gilmore and Ms Breathnach would be lessened by running jointly.
Their only hope would be that a well-packaged and presented new political force might attract sufficient of the volatile middle class voters of Dun Laoghaire - the most liberal in the State - to give it two seats. To do this it would have to unseat one of two relatively high-profile deputies - Ms Mary Hanafin of Fianna Fail and Ms Monica Barnes of Fine Gael.
Cork North Central and Cork South Central
On the face of it, Cork South Central should be relatively straightforward. Labour's Mr Toddy O'Sullivan lost his seat last time, but Democratic Left did not contest the constituency at all. However, now there is speculation that Democratic Left's Ms Kathleen Lynch might cross the city from Cork North Central where she lost her seat in 1997. This would be to contest the by-election caused by the death of Mr Hugh Coveney, which is expected next spring.
Of course just one candidate could run in a by-election, so a tough decision would have to be made here early on. In Cork North Central, Ms Lynch would be the obvious leading candidate, but Labour's organisation is active and believed to be reluctant to become simply a support organisation for a DL candidate regarded for so long as the main opposition.