A Mexican leftist leader has rallied thousands in Mexico City to oppose President Enrique Pena Nieto\'s proposal to open the state-owned oil sector to profit-sharing contracts with private firms, AP reported. Andres Manuel Lopez Obrador calls the reform proposal \"treason.\" The former presidential candidate said Sunday that Mexico\'s proven reserves lie on land and in shallow coastal waters, and no private firms are needed to drill for that oil. Pena Nieto proposed the reform in August, saying state-owned oil monopoly Pemex needs foreign expertise and technology in shale gas and deep-water reserves. Pena Nieto pledged to announce another reform later Sunday, to rework the country\'s inefficient tax policy. Lopez Obrador claims the president will tax Mexicans more to replace revenue lost because of the planned oil privatization.