Opposition TDs cannot compromise on the issue of Dáil speaking time, Sinn Féin TD David Cullinane has said.
It comes as Government TDs are likely to try to push through plans to allow members of the Regional Independent technical group to form a "hybrid" group across both Government and Opposition at Tuesday's Dáil reform committee.
However, Opposition TDs on the committee have already warned against such a move, saying they are likely to disrupt Dáil business on Wednesday if the Government plan is forced through.
Mr Cullinane also branded the proposal as a "grubby deal and stroke politics".
Speaking on RTÉ's Saturday with Colm Ó Mongáin, he said he did not want to see "unruly scenes" in the Dáil next week but the Coalition was trying to "muddy the waters" between those who are Government TDs and those who are in the Opposition.
He said Taoiseach Micheál Martin and Tánaiste Simon Harris do not want to tell Independent TD Michael Lowry it is "not acceptable" for a TD who backs the Government to secure opposition speaking rights.
Mr Cullinane said that the row could be "sorted very quickly" by Mr Martin and Mr Harris.
He asked: "What hold does Michael Lowry have over this Government?"
Speaking on the same programme, Minister of State Emer Higgins said the Government wants to find a compromise which is "politically acceptable to everyone".
She said under the Coalition's plan, giving speaking rights to Mr Lowry's technical group will not eat into opposition speaking time.
"That has been fixed," she said.
She said there is an urgent need to have the Dáil "functioning properly", and that meant ensuring that every member has the ability to speak.
Asked if Mr Lowry was a Government TD, she said: "We view him as an Independent."
Ms Higgins added that the issue of speaking rights did not come-up in any negotiations on a Programme for Government.
People Before Profit TD Paul Murphy said four meetings of the Dáil Reform Committee had been "ultimately unproductive" because, he claimed, Mr Lowry is determined to "have his cake and eat it".
He branded the proposal to name the Regional Independent technical group as non-aligned as "a stroke" which will undermine the Opposition's ability to hold the Government to account.
Mr Murphy said his party "cannot go along with a lie" in which a technical group is accorded the speaking rights of opposition parties and groups.
He added "it's not true" that Mr Lowry is non-aligned and said he is a Government TD.
Asked what will happen if the Government uses its Dáil majority to vote through the proposal, Mr Murphy replied: "We will not accept that."
Yesterday, Opposition party leaders Mary Lou McDonald of Sinn Féin, Cian O'Callaghan who is acting leader for the Social Democrats, Michael Collins of Independent Ireland, Labour leader Ivana Bacik, and Richard Boyd Barrett of Solidarity-People Before Profit wrote to the Taoiseach.
"We write to express our strong opposition to this Government proposal; to designate the Regional Independents as an 'informal technical grouping of unaligned members/Hybrid Group'.
"Your proposal to amend standing orders, ostensibly to allocate additional time for leaders and priority questions without reducing any party's time, is a transparent attempt to benefit this so-called 'informal unaligned grouping'. This is entirely unacceptable," the letter said.
"The Regional Independents are aligned with the Government, having negotiated a political deal with Fianna Fáil and Fine Gael to facilitate, among other things, your election as Taoiseach.
"As the combined Opposition, we will defend the separation of powers between our parliament as the legislature and the Government as the executive," it added.
"Despite taking a week to bring forward this proposal, it is clear the Government's position remains unchanged - granting special parliamentary privileges to a group that is not in Opposition.
"This attempt to designate the Regional Independents as an 'informal technical grouping of unaligned members/hybrid group' and to manipulate speaking time to favour them is fundamentally flawed and must be abandoned.
"The Government must swiftly reconsider its stance and uphold a rules-based approach that respects our parliamentary democracy and how it functions, the clear distinction between Government and Opposition, and the mandates of deputies who serve in either role," it said.
