There is now a real prospect of the Seanad being abolished in the next two years following a decision by the Labour Party to advocate its scrapping.

Labour's new major policy document on political and institutional reform, to be launched on Thursday, will bluntly state that the "case for the retention of Seanad Eireann has failed" and a "strong single-chamber" parliament with "real legislative and oversight powers" is required.

Given that Fine Gael has already committed itself to the Seanad's abolition, and the fact that the two parties are almost certain to form the next government, a constitutional referendum on this issue now appears inevitable within the next two years.

Labour's new document – New Government, Better Government: Changing a Broken System – proposes establishing a 90-member constitutional convention with a mandate to review the Constitution and draft a reformed one within a year.

And it says it will bring its case for abolishing the Seanad to this constitutional convention, which will consider all the options because "ultimately, the decision will be for the people by way of a referendum".

The policy document – drawn up by spokesman on constitutional matters and law reform Brendan Howlin and endorsed by the parliamentary party – says maintaining the Seanad in its current form is "clearly unacceptable". The two options are abolition or "changing the nature of the Seanad" by creating a new electorate, though not one directly representative of the people, as this was the role of the Dáil.

However, Labour has come to the view that "the case for the retention of the Seanad Eireann has failed". It says it was "not possible to identify any bodies or sections in our society that deserve (because they are university graduates or county councillors, for example) to be singled out as constituting a special and separate electorate, entitled to vote for their own separate House of the Oireachtas".

Labour stops short of proposing a specific new electoral system, but it does call for a "national and inclusive debate about the system of electing members of Dáil Eireann".

The document also proposes significant reform of the Dáil: a 50% increase in sitting days including Fridays; an end to the government monopoly on legislation and enhanced roles for legislative committees. Labour is also committed to repealing the Officials Secrets Act; restoring the Freedom of Information Act – including extending its remit to the Garda Síochána – advocating a constitutional amendment to provide for parliamentary inquiries and further restricting contributions to political parties and candidates.