Mexico's powerful CCE business lobby on March 12 urged the leftist front-runner for a July 1 presidential election to stop questioning major planks of the government's economic agenda lest it damage investment.

Andres Manuel Lopez Obrador, who has led opinion polls by a wide margin for weeks, has gradually moderated his rhetoric and his leading advisers have sought to reassure investors that he will not be an economic liability as president. However, his threats to scrap a new Mexico City airport already under construction and review oil and gas exploration and production contracts issued under a 2013-2014 energy reform still worry some investors.

"As we've said, you can't ask the private sector to take part in building a better country at the same time as undermining certainty and the rule of law as conditions for fostering investment," Juan Pablo Castanon, president of the CCE lobby, an umbrella group for business groups, said at an event in Mexico City.

"For this reason, we business folk demand guarantees that the contracts awarded under the energy reform and for the new airport will be respected," he added. "In a country governed by the rule of law, contracts are honored, and cannot be subject to the will or interpretation of a sitting government."

On Monday, Lopez Obrador said he still planned to scrap the new airport, but added he was not going to ignore contracts awarded and bonds issued for the project.

"We will respect construction contracts. Those that have those contracts don't have to worry," he said. "We will respect the bonds ... we're going to solve the problem without affecting investments."

Lopez Obrador's energy adviser has said that while publicly available versions of the energy contracts appear to be without problems, further investigation was needed to ensure corruption had not tainted the awarding process.

The business community was also worried there were candidates and campaign teams already casting doubt on the validity of the election "depending on who the winner is," Castanon said, without mentioning Lopez Obrador or his MORENA party.

Castanon's comments follow a speech by Lopez Obrador last week, in which he stuck to promises to not build the airport at the current construction site and warned there could be protests if he lost by fraud.

The former mayor of Mexico City, who was runner-up in the previous two elections, organized massive protests when he was narrowly beaten in 2006.