MR Bertie Ahern and Ms Mary Harney will question the Taoiseach in the Dail tomorrow on his attempt to influence the vote on the Scott arms for Iraq report in the House of Commons.
The leaders of Fianna Fail and the Progressive Democrats will be responding to an Irish Times report that Mr Bruton asked the SDLP leader, Mr John Hume, to ease Mr John Major's difficulties by abstaining. The request is believed to have been made just hours before the crucial division last Monday night, during a lengthy telephone conversation initiated by Mr Bruton.
It was confirmed yesterday that the Tanaiste, Mr Spring, knew nothing about the Taoiseach's intervention until last Friday.
The Government press secretary, accompanying the Taoiseach at the EU-ASEAN summit in Bangkok, would say only that Mr Bruton had "many confidential consultations in his successful pursuit of his goal of getting a fixed date for all party negotiations, and of removing all obstacles to that. These will remain confidential."
The Fianna Fail leader, Mr Ahern, stated yesterday that it was not the role of the Taoiseach "to be assisting the British government as assistant whip hours before a vote". He would be asking in the Dail exactly what was his role in this matter.
Mr Ahern conceded that he had no confirmation that Mr Bruton made the request, but it seemed from reports from Bangkok that he did it in some form.
"Remember that it wasn't on a Northern Ireland related issue, he continued. "If it was, I could perhaps understand that the Taoiseach would be endeavouring to take risks to try to move a process forward. But the Scott report was about a very serious issue within the British jurisdiction and nothing to do with the Taoiseach or anyone else in Irish politics."
If Mr Bruton had put pressure on Mr Hume to vote on an internal British matter that had been followed by a major judicial report, said Mr Ahern, it was improper for him to do so.
The PD leader, Ms Harney, said that if there was any truth in reports that the Taoiseach attempted to influence the outcome of the Westminster vote then it was a very serious and disturbing matter.
"It would be completely inappropriate for the Irish Taoiseach to interfere in the domestic affairs of another country, just as inappropriate, in fact, as it would have been for John Major to attempt to influence Dick Spring and the Labour Party at the time of the fall of the last government in the autumn of 1994," she added.
The Minister of State for Foreign Affairs, Ms Joan Burton, told a Channel 4 programme yesterday of her "surprise" at Mr Bruton's reported intervention with Mr Hume.
"I have only seen the reports," she said, "and I have to say as a member of the Irish Labour Party I am very aware of the SDLP's traditional links and associations with the British Labour Party. So the idea that the SDLP would not vote with the British Labour Party I would find rather surprising.
The Shadow Northern Ireland Secretary, Ms Mo Mowlam, said she would not "comment on a non issue" until Mr Hume makes a statement on the matter.
Ms Mowlam insisted yesterday that despite Mr Hume's earlier comments to The Irish Times, that he was neither confirming nor denying a telephone conversation with Mr Bruton, she would not be making any comment "until John Hume makes a statement".