The front-runner in Mexico’s presidential race would hit the brakes on the rapid pace of private investment in the country’s newly opened oil-and-gas sector if he wins the July election, a key adviser to Andrés Manuel López Obrador says. An administration led by Mr. López Obrador, a leftist nationalist, would freeze the oil auction process at least until some “successful” results are seen from the first exploration and production blocks tendered in 2015, said Congresswoman Rocío Nahle, the candidate’s top energy adviser and his pick to become energy minister in a future cabinet. Ms. Nahle, in an interview at her office in Mexico’s lower house of Congress, offered few details on how results would be judged. Investors are wary of a López Obrador victory primarily because of his opposition to Mexico’s recent energy overhaul, which put an end to eight decades of the state’s monopoly in the oil […]