Abolishing the Seanad will lead to a political elite in the Dail running the country without any scrutiny, campaigners have warned.
Former tanaiste and justice minister Michael McDowell said Ireland was in danger of mutilating the Constitution if a referendum to abolish the upper house of the Oireachtas is passed.
"(It would) concentrate more power in the hands of a dysfunctional executive, over whom there would be no checks and balances after this," Mr McDowell said.
The barrister and former Progressive Democrat TD is on the steering group of Democracy Matters - a band of campaigners demanding the reform of the Seanad, as opposed to its abolition. The group has insisted it is not interested in retaining the house in its current form, but reforming it to give it more powers to be able to hold the Government to account.
Campaigner Diarmaid Ferriter described the Seanad as "toothless", while group chairman and former senator Joe O'Toole said it was a "failing structure". Mr O'Toole also warned that Government plans to urge the public to vote for its abolition - when the referendum takes place in the autumn - were an attempt to "power grab".
"We need to stop this power grab," Mr O'Toole said. "We need to stop the house that has become a creature of the political parties."
He said removing the Seanad would leave an all-powerful Dail, which he described as "dysfunctional". He also said the Dail was run by the "political elite" - Cabinet ministers and their departments. He added even Government TDs, while elected by the public, were constrained by the whip system, which dictates what policies they can and cannot support.
Mr Ferriter insisted the Seanad was therefore necessary to scrutinise the Dail. "We need more scrutiny, we need more oversight politically considering the state we are in in contemporary Ireland," he said.
The professor of modern Irish history at University College Dublin added that the alternative of scrapping the Seanad would be "aggressively anti-democratic".
"It will inevitably copper-fasten power with a very small elite and it will leave us in a worse position than we are in now," he said. "Handing absolute power to a dysfunctional Dail which is already just a servant to an executive beggars belief."