The eight cardinals, who were appointed by Pope Francis in April, have been briefed to revise the constitution, known as Pastor Bonus and drawn up in 1988 by Pope John Paul, in a bid to give greater voice to bishops around the world.
Cardinal Oscar Rodriguez Maradiaga, the group's leader, said that at tomorrow's meeting they would go much further than just change "this and that".
"No, that constitution is over," he said in a television interview. "Now, it is something different. We need to write something different," he added.
The suggestion of drastic reforms to the Vatican's constitution follows several reformist comments by the Pope. He has said it was not up to him to "judge" homosexuals and that atheism and agnoticism are tolerable if people retain a good consience.
Gerard O'Connell, a Vatican analyst, said that the proposed rule changes were a "rupture after a century of increasing centralisation".
"Cardinal Maradiaga is hinting that the Pope is asking the fundamental question: 'What can be decided in Rome and what at local level? How can the Roman Curia serve bishops instead of being an office of censure and control?'"
Mr O'Connell cited Japanese bishops as examples of victims of the Vatican's centralisation.
"They must ask advice from Rome on the correct Japanese to use in their liturgies, yet you would think they would be the best judge."
Over the weekend, Pope Francis gave another clear indication that he sees the Vatican as a hotbed of intrigue and power struggles when he suggested Vatican policemen should crack down on gossip as well as looking out for intruders.
Defining gossip as the devil's work, "a forbidden language" and "a war waged with the tongue", he told gendarmes gathered for Mass to tell any gossipers: "Here, there can be none of that: walk out of St Anne's Gate. Go outside and talk there!"
Cardinals gathering in Rome before Pope Francis was elected in March complained that Vatican officials had become a self-serving elite indifferent to the needs of dioceses worldwide.
Cardinal Rodriguez Maradiaga said his group had received suggestions on Vatican reform from around the world, including 80 pages of suggestions from Latin America.
The convergence on a few main themes suggested God's will was at work, he said. "You cannot have millions of Catholics in the world suggesting the same unless the Holy Spirit is inspiring."