MEXICO CITY (Reuters) - Faced with tough questions last week from six journalists on live television, Mexican presidential front-runner Andres Manuel Lopez Obrador leaned back in his chair with a twinkle in his eye, laughing off criticism, at times making fun of himself.

FILE PHOTO: Leftist front-runner Andres Manuel Lopez Obrador of the National Regeneration Movement (MORENA) addresses the audience during a conference organised by the Mexican Construction Industry Association in Guadalajara, Mexico March 23, 2018. REUTERS/Henry Romero/File Photo

On the street the next day, the leftist’s tone changed when he castigated Mexico’s business elite, accusing them of corruption in the $13 billion construction of a new Mexico City airport he threatens to scrap if elected.

The peremptory dismissal of the bosses jarred with the more moderate image Lopez Obrador has cultivated to build a strong lead ahead of the July 1 vote.

The outburst deflected attention from his opponents’ woes and undermined the vision of a smiling, avuncular patriot he has sought to project. Adversaries jumped on the opportunity to paint an old portrait of him as a short-tempered radical and divisive nationalist who cannot be trusted with the economy.

A Lopez Obrador victory could usher in a Mexican government less accommodating toward the United States, where president Donald Trump has stoked trade tensions with Mexico and aggressively moved to curb immigration.

Lopez Obrador has backed the North American Free Trade Agreement (NAFTA), but his plan to review newly issued oil contracts sparked worries he will deter foreign investment.

Critics and supporters alike say the 64-year-old has stuck to his principles in the dozen years he has spent pursuing the presidency. Meanwhile, his main rivals have entered government and exhausted their political capital. Voters are angry about corruption, gang violence and chronic inequality.

The presidential campaign formally gets underway on Friday. As he runs for a third time, the odds have never looked so favorable for Lopez Obrador, who cheerily brushes off warnings that his criticism of business will alarm investors.

“They want to frighten you,” he said in a video post last week. “But it won’t work. People don’t want corruption, they’re sick of a few people bent on ripping off the country.”

Most polls give a double-digit lead to the baseball fan, who wore a cap and t-shirt in a video post on Wednesday, and pitched a ball to applause and laughter after pledging to send a “curve ball” to Trump.

Lopez Obrador says his country must reduce its dependence on foreign influence. Trump’s threats to make Mexico pay for a border wall and to tear up NAFTA have played into his hands.

‘RADICAL BASE’

Often referred to by his initials as AMLO, Lopez Obrador has traversed the length and breadth of the country almost non-stop since he launched his first presidential bid in 2005.

After narrowly losing to conservative Felipe Calderon in the 2006 election, he claimed the election was stolen and brought much of Mexico City to a standstill with massive street protests, declaring “to hell with your institutions.”

The protests damaged his popularity, but he continued to blast Calderon’s National Action Party (PAN), then the centrist Institutional Revolutionary Party (PRI) of his successor Enrique Pena Nieto, as abettors of corruption and social unrest.

A string of graft scandals and drug cartel violence under the PRI have helped his message resonate. By 2015 some senior officials were saying privately the election was AMLO’s to lose.

Since then, he has alternated between seeking to lure support away from rival parties and playing to his leftist base with attacks on the airport and the government’s opening of the oil and gas industry.

“The main thing that he has to deal with is his base. He’s very much like Donald Trump in that way,” said Jorge Castaneda, co-campaign manager of Lopez Obrador’s closest rival, 39-year-old Ricardo Anaya, who heads a right-left coalition.

“Which is why those people in Mexico who think he will become a moderate or a reasonable person are misunderstanding one: how radical his base is. And two: how careful he is never to lose touch with his base.”

No longer so openly contemptuous of Mexico’s frail institutions, Lopez Obrador has expanded that base by courting support from social conservatives opposed to same-sex marriage, drug legalization and abortion.

He soon modified his hard line on the airport, proposing that a group of experts analyze the project, which the government says would cost $6.6 billion to cancel.

Tatiana Clouthier, a campaign coordinator who joined Lopez Obrador after long ties with the PAN, said this showed political maturity and a move toward the center.

“The great transformations in the world come via a pendulum between extremes,” she said.

Lopez Obrador has been vague on contentious issues, saying he will consult the public. When journalists on Milenio television pressed for specifics on drug policy last week, he smiled and demurred.

“In politics it’s not black and white,” he said. “There are times when you have to be nuanced.”