Sinn Féin and the two remaining Independent TDs will lose the speaking rights they had in the last Dáil if the proposed coalition government goes ahead.
Sinn Féin's four TDs and Independents Tony Gregory and Finian McGrath would be one short of the seven TDs they need to form a "technical group" which entitles them to extensive speaking and debating rights in the Dáil.
Talks are currently taking place on the formation of a government that would comprise Fianna Fáil, the Green Party, the Progressive Democrats, and Independent TDs Beverley Flynn, Jackie Healy-Rae and Michael Lowry.
Mr Gregory said yesterday that such a situation "virtually prevents us having any speaking rights at all other than in an adjournment debate".
Without a technical group they would also not be able to speak during leaders' questions, which would be confined to the Fine Gael and Labour leaders, he said. In the last Dáil, Socialist Party TD Joe Higgins spoke on behalf of the Independents during those questions.
Mr Gregory said the TDs would not be allowed attend whips' meetings when the government and opposition parties discuss the proposed order of business, and could not ask priority questions during ministers' question time.
The Dublin Central TD pointed out that the Green Party was "very vocal on Dáil reform and the rights of smaller parties" and he hoped that would be on the agenda during the current negotiations.
He added that if Mr Lowry remained on the Opposition benches they would have seven TDs for a technical group.
Mr Lowry said yesterday "that is the first time that has been drawn to my attention", but added that his principal concern was his constituents, not himself or other politicians.
The former Fine Gael minister, who was an inactive member of the technical group in the last Dáil, said he would like to see all Independents and those on the Opposition benches have proper entitlements to speaking and debating rights, but "I don't see myself having an onus to deliver that" but rather to deliver for "those who elected me, the people in North Tipperary".
Meanwhile, the Bill abolishing stamp duty for all first-time buyers regardless of the value of the house will not be before today's Cabinet meeting.
Taoiseach Bertie Ahern confirmed at the weekend that a Bill was being prepared to allow for major reform of stamp duty as promised by Fianna Fáil in its election manifesto.
The Bill is still being drafted and is not expected to be circulated until the new Dáil is in session if Mr Ahern succeeds in forming a government.
All Ministers - including Tánaiste Michael McDowell, who lost his seat in the general election - will attend today's Cabinet meeting, the last one of the 29th Dáil.
The first post-election meeting of the Fine Gael parliamentary party takes place in Leinster House today with all its 51 TDs expected to attend.