Why is a pre-election pact so unpalatable?

Are we looking at a straight choice between an eventual Sinn Féin led Government?

Or something else? Most pundits ( and not a few ordinary citizens), agree that short of a seismic or miraculous change in support figures, the most likely Government to emerge after the General Election will be a Fianna Fáil /Fine Gael /Labour minority Government — with independent ( and/or ‘new party’), participation or support.

No combination of any two of the ‘old’ parties will reach the magic 79 seats. Even the super-rainbow outlined above will need some heavy welding to hammer it together.