FIANNA Fail leader Michael Martin accused Taoiseach Enda Kenny of operating a dictatorial 'una duce, una voce' style of leadership where dissension is not tolerated.
Mr Martin's scathing reference to Italian dictator Benito Mussolini's famed leadership motto came as he again warned of the problems in concentrating all Irish political power in a single chamber parliament.
The FF leader, speaking at his party's Waterford 'think in', said he "wanted to choose his words carefully" about the matter.
But he warned that crucial legislation was being rammed through the Dail by the Government thanks to its record majority with Mr Kenny also determined to smash dissent within his own party.
"How would I put it...(the) una duce, una voce approach of Enda Kenny and his people. Such a dictatorial approach that people are almost afraid to articulate their view," he said.
The Fascist motto was famously quoted by former Government Press Secretary PJ Mara in reference to FF's need for unity under former Taoiseach Charles Haughey.
Mr Martin said he was taken aback by FG's ruthless treatment of those who hold dissenting opinions.
"I mean Sen Maurice Cummins (FG) said it. He said: 'Look, I am going to vote against it (Seanad abolition) but I am not campaigning'. He said it in a hurry but he clearly articulated his position," he added.
Mr Kenny today warned that it would be "very difficult" for the five FG TDs who lost the whip due to their stance on certain issues, most notably the abortion debate, to re-enter the party.
He said the TDs had effectively "self-expelled themselves" by their failure to abide by the FG whip.
Mr Martin said the crushing of dissension, the ramming through the Dail of key legislation such as the social welfare bill and property tax bill and the refusal to allow a proper public debate on the Seanad referendum were matters of great concern.
Mr Martin said Mr Kenny was now "running scared" of a public debate on Seanad reform as he repeated his challenge to the Fine Gael leader to discuss the issues over the upper house's abolition with him in an RTE debate.
"I was extremely disappointed by the Taoiseach's response to questions put to him on RTE's 'Morning Ireland' where he suggested there could be debate on this in the Dail. He knows full well there cannot be," Mr Martin said.
"I think he is insulting the intelligence of the public. He needs to answer why he will not debate in public, head-to-head, on one or both of our broadcasting stations the issues of the abolition of the Seanad."
He repeated his challenge to Mr Kenny to agree to a TV debate as he warned that he believed there were "a significant number of people" within both FG and Labour who oppose the abolition of the Seanad.