Taoiseach Enda Kenny has ignored a challenge from the Opposition to a live TV debate on the abolition of the Seanad.
Fianna Fáil leader Micheal Martin threw down the gauntlet just minutes before Fine Gael officially launched its campaign for a Yes vote in the referendum on the scrapping of the upper house.
"Deputy Martin will have his opportunity in Leaders' Questions," Mr Kenny said.
The Taoiseach, who described the Seanad as a "powerless, elitist second house", also rejected accusations of attempting to grab more powers for the Government.
"This is not a question of an egotistical power grab, this is about the people," Mr Kenny said.
The public vote on whether the Seanad should be abolished will be held on October 4.
The Taoiseach said the abolition of the Seanad is just one step in the Government's overall plans for political reform.
He said ministers would publish a string of proposed changes to the Dáil this week, which are likely to include longer sitting hours, new committees to consider legislation at different stages and wider consultation.
Mr Kenny also dismissed concerns that abolishing the Seanad would mean there would be no one to act as a watchdog to the Government.
"It is the constitutional responsibility of Dail Eireann to hold the Government to account. It is not vested in the Seanad," he said.
The upper house is able to delay legislation but cannot block it, and this power has only been used twice in 75 years.
Fine Gael has insisted that scrapping the Seanad would save the state €20m a year and would result in 33% fewer politicians.
"Do we want politics which is more effective, more comprehensive, less costly, more transparent and more accountable?" Mr Kenny said.
Launching Fianna Fáil's campaign for a No vote in the referendum, Mr Martin claimed the abolition of the Seanad would scrap any chance of true political reform.
"If passed, this amendment will deliver no reform to the substance of Irish politics," Mr Martin said.
"In fact, it will make matters worse because it will cement absolute ministerial control over the political system, and it will mark the formal end of any chance to achieving real political reform."
The Fianna Fáil leader called for a live debate with the Taoiseach in the run-up to the public vote.
He said he would be willing to go head-to-head on any outlet willing to host the showdown.
He claimed that if Mr Kenny refused, it would send a message to the public of an arrogant Government that already has too much power.
Sinn Féin recently launched its own campaign for the abolition of the Seanad.
The opposition party, which described the upper house as "an affront to democracy", has since launched its own proposals for political reform.
Deputy leader Mary Lou McDonald said it would consider gender quotas, reducing the voting age, partial list systems and extending voting rights for northern citizens among its suite of proposed changes to the system.