A commitment to hold a referendum to allow Irish emigrants and citizens living in Northern Ireland to vote in presidential elections should be prioritised by the next government, the outgoing senator for the diaspora has said.

In a letter to Taoiseach Leo Varadkar and Fianna Fáil leader Micheál Martin, Senator Billy Lawless called for a referendum to be held in 2021 and for an electoral commission to be established.

“We can’t have a Republic with two types of citizens – a first class with the right to vote, and a second class with no rights at all,” he writes, adding that Ireland’s electoral system “now denies the vote to well over a third of all Irish citizens.”

It is understood that Mr Lawless has reached out to the smaller parties as government formation talks begin in earnest.

The Chicago-based senator, who was appointed by Enda Kenny in 2016, said that while a promised referendum on the issue had been deferred because of local and byelections and Brexit, “the time has now come for the next government to hold this referendum.”

“As a nation we are behind the times when it comes to democratic practices that are accepted and well established in the EU and around the world in the global democratic community,” he writes.

Approximately 130 countries around the world permit citizens living abroad to vote in elections. But the issue is particularly sensitive for Ireland given the size of the diaspora and the fact that hundreds of thousands of Irish citizens live in Northern Ireland.

In 2016 the Constitutional Convention voted in favour of extending the vote in presidential elections to Irish people living abroad. The current Government had given approval last year to draft the general scheme of a Bill to amend the Constitution to extend voting rights to the diaspora, with a referendum expected in October, but the process was delayed.

The issue of extending the franchise to Irish people living abroad has also come to the forefront in recent years with the #HomeToVote campaign which saw thousands of Irish citizens returning to Ireland from abroad to vote in the referendums on marriage equality and the repeal of the Eighth Amendment.

In his letter to Mr Varadkar and Mr Martin, Mr Lawless also raises the question of voter representation, noting that Ireland is an international outlier in terms of the lack of postal voting as well as its denial of voting rights to emigrants.

He highlights a 2018 study by the Electoral Integrity Project (EIP) which ranked Ireland at 137 when it comes to the integrity of voter registration. In particular, the report highlighted the absence of systems to encourage voter registration, especially among young people, in Ireland, as well as the lack of absentee voting. Mr Lawless points to the fact that university graduates have been permitted to use a postal vote in Seanad elections since 1937, but postal voting for other Irish citizens is not allowed.

In addition to the recommendations of the constitutional convention, the 2018 Citizens’ Assembly recommended a series of reforms to increase voter turnout for referenda, including weekend voting, online voting and postal voting.