They piled heavy chairs around the speaker's platform, while their colleagues in the Senate began fasting to demand that Congress schedule a national debate on the energy bill backed by President Felipe Calderon. They have not said what such a debate would entail.
The coordinator of Mexico's ruling conservative party in the Senate, Santiago Creel, said Monday it was unlikely Congress would be able to approve the bill by April 30, when the legislative session ends.
Oil production in Mexico, one of the top suppliers to the United States, is declining, and reform advocates say state oil company Petroleos Mexicanos, or Pemex, needs outside resources to explore for reserves. The bill would allow Pemex to partner with private companies for exploration and refining.
Opponents claim the bill would lead toward selling off parts of Pemex and threaten national sovereignty.
Sen. Carlos Navarrete, leader of the leftist Democratic Revolution Party bloc, vowed disruptions would continue.
"We have made a gigantic effort - at enormous political and physical costs - to push for a wider debate," he told W Radio on Monday.
The tactics in Congress are supported by Mexico's foremost leftist leader, former presidential candidate Andres Manuel Lopez Obrador, who drew more than 100,000 supporters to a Sunday rally against the oil reform in Mexico City's central square.
Last week, lawmakers from Lopez Obrador's Democratic Revolution Party, the second largest bloc in Congress, and two minor parties stormed the podiums in the house and Senate after Calderon introduced the bill.
Lopez Obrador said the bill aims to privatize Pemex, allowing Mexico's oil revenues - which provide for nearly 40 percent of the national budget - to go to private and foreign companies.
Calderon has repeatedly denied he plans to privatize Pemex.