Venezuela's President Nicolas Maduro says he will form a new constituent National Assembly with powers to rewrite the constitution.
The new body will be made up of ordinary citizens and would circumvent the opposition-controlled National Assembly.
The opposition leader, Henrique Capriles, said such an assembly would be a constitutional fraud.
Opponents of Mr Maduro have held the latest in a month of bloody protests.
Mr Maduro said the body would defuse the country's political crisis by blocking opponents threatening the country.
He said it would be made up of pro-government worker's groups along with civic society groups.Image copyright AFP Image caption Opposition activists clashed with riot police during May Day demonstrations in Caracas Image copyright AFP Image caption Pro-government marchers carried cut outs of Mr Maduro's mentor and predecessor, Hugo Chavez
The National Assembly has been calling for Mr Maduro to resign as the country reels under severe economic hardship.
"I don't want a civil war," Mr Maduro told a May Day rally of his supporters in the capital, Caracas.
Elsewhere across the city security forces fired tear gas as young men threw stones and petrol bombs after May Day opposition marches were blocked from reaching government buildings.
Julio Borges, the president of the country's National Assembly, said the attempt to set up the new constituent assembly was an attempt to destroy Venezuelans' right to vote and another step towards a political coup.
Demonstrators first took to the streets on 1 April to demand elections, after the courts tried to strengthen the president's grip on power.
Marches in various cities descended into clashes between riot police and protesters, which have left 28 people dead.