Leftist politicians in Mexico who last week stormed both houses of Congress have vowed to remain in protest at planned reform of the state oil giant.
The government says the Pemex oil company needs outside investment to boost falling production and increase exploration for new reserves.
But the protesting deputies and senators argue that this will lead to a creeping privatisation of Pemex.
The protesters want a broad debate on Pemex, in state hands for 70 years.
Leftist deputies and senators have been camped out on the floors of the upper and lower houses since they took over the Congress building last week.
In the lower house, lawmakers from the Democratic Revolution Party (PRD) and two other smaller parties have piled chairs around the speaker's platform.
The protesters have, however, called off a brief hunger strike
In a bid to break the deadlock, members of President Felipe Calderon's National Action Party (Pan) and the Institutional Revolutionary Party (PRI) offered to debate the energy reforms for 50 days followed by a vote in an extraordinary session.
But opponents of the bill rejected this.
National treasure
"We will continue to insist on the need for a wide open national debate... we ask that Congress's recess be used for this debate," Senator Dante Delgado was quoted as saying by Mexican newspaper Reforma.
Congress ends its spring session on 30 April, resuming on 1 September.
President Calderon last week unveiled an energy reform bill that would give Pemex more freedom to make decisions, contract out work, and manage its budget to reinvest in production and exploration.
Mr Calderon stressed that this did not mean any form of privatisation but was aimed at improving exploration to access the deeper reserves of oil in the Gulf of Mexico.
But opponents of the moves say it would undermine national sovereignty. They believe foreign oil companies will come in and take a share of Mexico's oil profits.
The government insists they will only be offered incentive payments.
Oil revenue constitutes some 40% of the federal budget.
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