The dominant figure on the Mexican left for a decade, Andres Manuel Lopez Obrador, formally signed up on Tuesday with the new political party he hopes will become a mass movement.

"We begin this membership campaign with the goal of recruiting and adding millions of Mexicans ... who are convinced of the necessity of genuine change," the two-time presidential candidate told supporters in the Zocalo, this capital's giant main square.

Lopez Obrador ally Marti Batres delivered to the Federal Electoral Institute the documents needed to begin the process of turning the Morena organization into a registered political party eligible for public funding.

Morena must sign up at least 220,000 members and hold assemblies by the end of this year to qualify for the 2015 mid-term legislative elections.

"We have to keep fighting to transform our country," Lopez Obrador said Tuesday. "We are convinced that if there is not a regime change, we won't find a way out, either as a people or a nation."

The former Mexico City mayor barely lost the 2006 presidential election and attributed his second-place finish in last year's vote to chicanery by the victorious Institutional Revolutionary Party, or PRI, which enjoyed a defacto monopoly on power from 1929-2000.

Though he was one of PRI renegades who established the nominally leftist PRD in the late 1980s, Lopez Obrador quit that party in September to establish Morena.

"We cannot abandon the people, we have to continue insisting until we achieve a change of regime, until we defeat the power mafia that again appropriated the government," Lopez Obrador said, referring to the return of the PRI. EFE