At an open air rally before thousands of supporters in red t-shirts, Maduro signed a document formally establishing the terms for electing members of a "constituent assembly" that will be tasked with drafting a new constitution.
His backers waved red, yellow and blue national flags in defiance of angry opposition protests after the death toll from weeks of clashes reached 53.
But the opposition-controlled National Assembly promptly rejected Maduro's plan.
Violence appeared to intensify in recent days with the opposition marching daily to demand early elections.
A man was doused in fuel and set alight on Sunday at a demo. Three people were shot dead late Monday in riots in the western state of Barinas.
The government and opposition accuse each other of sending armed groups to sow violence during demonstrations.
Constitutional maneuvers
Maduro has accused the opposition of "terrorism," and is resisting their calls for a vote on removing him from power.
The opposition blames him for an economic crisis that has caused shortages of food and medicine.
It says he plans to pack the "constituent assembly" with his supporters.
Maduro said 176 of the assembly's members will be drawn from certain civil groups, which the opposition say are traditionally loyal to him and his late predecessor Hugo Chavez.
In a move set to further inflame the opposition, Maduro said the constitutional body would sit in the chamber of the National Assembly legislature -- the only state institution nominally controlled by his opponents.
"What Nicolas Maduro has announced is nothing but a continuation of a coup against the constitution," said the opposition speaker of the legislature, Julio Borges.
"This National Assembly calls on Venezuelans to continue peaceful protests morning, noon and night in all corners of Venezuela until the constitution is respected."
Electoral specialist Eugenio Martinez said on Twitter that the constitutional assembly looked likely to be set up via "a made-to-measure election, a process designed to make the Chavista vote worth more than the opposition one."
Death toll hits 53
A total of 53 people have been killed during demonstrations, many of them shot, public prosecutors said on Tuesday. Looting has broken out in various cities.
A man was set alight on Sunday by a crowd who accused him of thieving. Maduro said he was targeted for being a government supporter.
Fresh riots broke out on Monday evening in the capital and Barinas.
"Venezuelans awake today in mourning for those murdered in our beloved Barinas. Such viciousness against our people!" opposition leader Henrique Capriles wrote on Twitter.
Opposition lawmakers called a session for Tuesday to discuss the violence.
Maduro resists
Elected in 2013, Maduro has resisted opposition efforts to remove him since January 2016.
He has said there will be presidential elections as scheduled next year, but not before.
Instead, he has angered the opposition by seeking constitutional reforms. His rivals say that aims to strengthen his grip on power and avoid elections.
Maduro retains the public backing of the military and control of most state institutions.
He says the crisis is an international conspiracy backed by the United States.
Venezuelans are struggling to buy food due to shortages and soaring inflation.
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