MEXICO CITY (Reuters) - A newly unveiled presidential contender for Mexico’s ruling party attacked his main leftist rival on Tuesday, accusing him of being obsessed by power, afraid of debate and unable to tackle corruption when he held public office.

Mexico's outgoing Finance Minister Jose Antonio Meade waves next to President Enrique Pena Nieto during an event where Pena Nieto announced the resignation of Antonio Meade, at Los Pinos presidential residence in Mexico City, Mexico November 27, 2017. REUTERS/Henry Romero

Jose Antonio Meade, who resigned as finance minister on Monday to run for the Institutional Revolutionary Party (PRI), sought to discredit former Mexico City mayor Andres Manuel Lopez Obrador, the early front-runner in the July 2018 election.

“I’m not afraid of Andres Manuel, I’m sure I’m going to beat him ... because there’s a fundamental difference,” Meade told Mexican radio. “What he’s about is hunger for power, and with me it’s about wanting to serve and construct.”

Graft scandals have battered the PRI’s credibility under President Enrique Pena Nieto, and senior officials regard Meade as a strong candidate because he has avoided the taint of corruption in office - and does not belong to the party.

The PRI does not begin registering candidates until Dec. 3 and will not elect its contender until Feb. 18. However, all the indications are that Meade will run to replace Pena Nieto, who is constitutionally barred from seeking re-election.

Lopez Obrador, runner-up in the past two elections, has spent years railing against graft, which promises to be a key campaign issue. Right after Meade signaled his intention to run, Lopez Obrador branded the PRI as corrupt and predictable.

Meade offered little detail of how he planned to root out corruption beyond pledging to strengthen institutions, echoing the rhetoric of Pena Nieto, whose approval ratings plumbed multi-year lows, partly due to failure to tackle the issue.

Instead Meade, 48, accused Lopez Obrador of seeking to avoid debate, and argued that his rival failed to root out corruption when he had the chance, as mayor of the capital.

“Whoever thinks that the answers to Mexico’s problems are about one person ... (or) are about being messianic ... is simplifying the complexity of building institutions that give us a nation of laws,” he said in another radio interview.

Meade, who has held most of the top cabinet jobs across two rival administrations, was at pains to stress his honesty, and said he had no skeletons in his closet.

“That’s why I feel very proud to look my children in the eyes, with them knowing that their dad has worked for Mexico with integrity and honor,” he said.