Andres Manuel Lopez Obrador, the Tabasco-born politician who narrowly lost out to President Felipe Calderon, is backing former Mexico City Mayor Alejandro Encinas in the centre-left opposition Party of the Democratic Revolution (PRD) leadership election on Sunday. The moderate wing of the PRD supports the leader of the New Left movement, Jesus Ortega. 

Encinas' performance will be good indicator of support for Obrador, who declared himself Mexico's legitimate president in 2006, leading to large-scale demonstrations in Mexico City.  However, this has undermined the party's popular support, and Lopez Obrador's standing, with many PRD legislators and governors now cooperating with Calderon, of the centre-right National Action Party (PAN), on some issues.

Encinas is the better funded candidate, and, in addition to support from Lopez Obrador loyalists -- who remain a strong force -- he may well benefit from growing concern within the PRD about impending legislation to liberalise the oil sector, allowing private investment to help state monopoly, Pemex, explore for deep water oil in the Gulf of Mexico. 

Nonetheless, there is significant dissatisfaction within the party at Lopez Obrador's confrontational approach, and a desire for the party to have a more central role in negotiations over key legislation. This means that Ortega may mount a strong challenge.

The one certainty about this week's race is that it will not heal the schisms that have formed within the party since Lopez Obrador's presidential defeat.  Even if Encinas wins, elements within the party - particularly state governors - will continue to work with the Calderon administration.  If Ortega clinches the leadership, the risk will grow of the party splitting, with Lopez Obrador using the Broad Progressive Front (FAP), which he formed in the aftermath of the presidential race, as the foundation for a new party.