Promises to radically reform the Dáil could mean just eight fewer TDs under a deal being hammered out by the coalition partners.
Environment Minister Phil Hogan said a commission would be set up next month to reduce the number of elected representatives based on the census figures.
But despite pre-election vows from Fine Gael to cut 20 Dail seats, he signalled that figure could now be less than half of what was pledged in their manifesto.
“We sought a mandate from the Irish people to change the way we do politics and to reform the system,” he said.
“We believe that by putting a proposal to abolish Seanad Eireann and reduce the number of TDs, we will achieve at least a 30% reduction in the number of members of the Oireachtas.”
With 166 TDs and 60 senators, that would equate to as few as eight less seats in the Dáil once the Seanad is scrapped. A referendum on abolishing the second house is expected next year.
Mr Hogan said there has been no agreement yet on new Dail numbers between Fine Gael and Labour.
While Labour also backs the abolition of the Seanad, the party made no pre-election commitments on reducing TDs.
The coalition deal struck between both parties agreed to cut seats but didn’t specify how many.
Mr Hogan said the constituency boundary commission, chaired by a High Court judge, will recommend the number within a government-designated band and under constitutional limits.
The move is expected to save between €10m and €12m, according to the minister.
Under the Constitution there must be at least one TD for every 20,000 to 30,000 people. There are currently 43 constituencies.
The Cabinet has also rubber-stamped proposals to hold all by-elections within six months and reduce the spending cap on presidential election campaigns.
Mr Hogan said the by-election timeframe would end the “farcical situation” of political parties being forced to take High Court challenges to fill seats left empty when a TD resigns or dies.
New limits on presidential campaigning, to be brought in before October’s election to Aras an Uachtarain, will chop spending limits from €1.3m to €750,000.
Candidates will be allowed reimbursements for expenses up to €200,000, down from €260,000.
Mr Hogan said the changes would allow for more frugal campaigns.