Voters go to the polls on Thursday to elect a 110-member forum, which will supply most of the negotiators for the inter-party talks due to open on 10 June.
The outbreak of verbal jousting appears to have its origin in worries within David Trimble's Ulster Unionist Party that its campaign is not going well. Reports are circulating that rival parties, principally the Rev Ian Paisley's Democratic Unionists and Robert McCartney's UK Unionists, are making a strong showing.
A poor performance for Mr Trimble would represent a serious blow to his credibility, in that he is regarded as the prime mover in pressing the Government to hold the election in the first place.
The various parties involved sought to portray rivals as being unsound on the issue of the union.
Mr Trimble's party yesterday called a news conference to warn voters against fracturing the Unionist vote, in the process launching a strong attack on Mr Paisley. John Taylor MP accused the DUP of "playing straight into the hands of Dublin", while Mr Trimble said Mr Paisley had formed an unholy alliance with John Hume's Social Democratic and Labour Party for the purpose of doing down the Ulster Unionists.
Mr Paisley, in a swift response, accused Mr Trimble of selling the pass by, he said, being prepared to put the 1920 Government of Ireland Act, which set up the state of Northern Ireland, on the negotiating table.
He said that Mr Trimble "dreaded" the DUP, adding: "He's not happy because he's losing out in this election."
Mr McCartney, of the smaller UK Unionists, said that Mr Trimble had turned down his suggestion of a united unionist front to fight the elections. Mr Trimble retorted: "Mr McCartney doesn't tell you that he broke off the discussion and rushed out of the door, pausing only to discharge an epithet in my direction."
With almost a dozen pro-union parties standing in the election, one Unionist nightmare scenario is that the vote would splinter in such a way that the SDLP could, for the first time ever, win most votes.
While not affecting any future negotiations, such an outcome would represent a major psychological setback for Unionism.