MEXICO CITY (Reuters) - Mexico’s leftist presidential front-runner, Andres Manuel Lopez Obrador, may allow more oil and gas fields to be auctioned off if elected on July 1, a top adviser said on Monday, striking a moderate tone days before the election.

FILE PHOTO: Mexico's presidential front-runner Andres Manuel Lopez Obrador of the National Regeneration Movement (MORENA) addresses supporters in Oaxaca, Mexico June 16, 2018. REUTERS/Jorge Luis Plata

Lopez Obrador, who has a commanding poll lead ahead of Sunday’s vote, has been a longstanding critic of the 2013-14 energy reform that opened up oil and gas production and exploration to private and foreign investors.

However, Alfonso Romo, his top business adviser and nominee for chief of staff, said Lopez Obrador was open to permitting more auctions if the process had not been tainted by wrongdoing.

Lopez Obrador has vowed to review outgoing President Enrique Pena Nieto’s energy overhaul, and threatened to cancel the reform if he found corruption in the awarding of contracts.

“The auctions are going to continue if everything we find is alright,” Romo said, noting that Lopez Obrador himself had taken the same message to investors. “He said it in New York. Andres Manuel, not Alfonso Romo.”

Romo, a business tycoon, reiterated his vote of confidence in the energy sector liberalization, saying he felt “very at ease” with the oil contracts he had reviewed so far.

Members of Lopez Obrador’s campaign team have sent out mixed signals on the reform, with some arguing Mexico should not be giving up its oil to private or foreign interests.

Romo said that Mexico needed to lower energy dependence on the United States, and if the private sector could help it do so, it should. He also said a Lopez Obrador government should consider allowing private investment in oil refining.

A Lopez Obrador government would also like to strengthen a “very undervalued” peso currency by boosting investor confidence and the rule of law, Romo said. He took pains to stress that a Lopez Obrador government did not plan to resort to intervention for that purpose.

“This government’s straitjacket will be that we don’t want to raise the debt,” Romo said. “And we will achieve it.”

The peso sank to a 1-1/2-year low this month, hit by a broad dollar rally, a deadlock in talks between the United States, Canada and Mexico to rework the North American Free Trade Agreement and some nerves ahead of the election.

Lopez Obrador, 64, was runner-up in the last two campaigns and has long been the foremost anti-establishment voice in Mexico. Some of his proposals, such as suspending the oil and gas auctions, have unnerved investors.

Romo said the process of revising the energy reform and its contracts should ideally be completed by about October. The next president will take office at the start of December.

Lopez Obrador, a former Mexico City mayor, holds a double-digit lead in all major opinion polls, although one survey on Monday showed his lead narrowing slightly.