More voices from Northern Ireland should be heard in the Irish Seanad, the Taoiseach said.
Leo Varadkar favoured reform of the Oireachtas upper house as part of a wider shake-up creating overseas "constituencies" of diaspora living in places such as North America and Europe.
He warned the prospect of processing millions of postal votes and certain provisions in the state's constitution made it a complicated task but added: "I very much want to see the voice of Northern Ireland represented in our Seanad."
The Taoiseach said the first Free State Senate, established after Irish independence, was intended to represent unionist voices; half its members were unionists.
"I definitely think that our Senate would add to our parliament if we had more people from Northern Ireland sitting in the Seanad.
"We have two now, possibly three, Ian Marshall most recently elected, but I think we could have more and that would definitely add to our parliament and that is something I would favour."
Mr Marshall is a unionist farmer who opposes Brexit.
The former president of the Ulster Farmers Union, from Markethill in Co Armagh, ran as an independent after being first approached by the Taoiseach to contest the election.
Sinn Fein's former Belfast Lord Mayor Niall O'Donnghaile also sits in the Seanad.
Billy Lawless, a Chicago restaurateur, has represented the diaspora there since 2016.
The house has 60 members. The Taoiseach nominates 11, six are elected by university graduates and 43 in Seanad panel elections representing sectors such as industry, culture and education.
The Irish constitution requires the use of postal votes and Mr Varadkar said it would not be an easy option to get one million votes from Northern Ireland and millions more worldwide.
"I would like to see people elected from international constituencies, North America, Europe and so on, representing our citizens overseas," he said.
He said obtaining millions of far-flung postal votes would be logistically complicated, expensive and perhaps not a good idea and would require constitutional change.
A new electoral register would need to be required to register people from around the world and voters would have to opt to be an elector on a certain panel, which could be "confusing".
Mr Varadkar said the panels were based on a papal encyclical from the 1930s and did not reflect the way modern society broke down.
He added: "This is not going to be a simple reform."