MEXICO CITY (AP) 鈥 Mexico鈥檚 leftist presidential front-runner is combative and unbending, and his personality-based campaign proclaiming honesty and fiery nationalism could set up a unique and combustible relationship with his northern counterpart should he win.

Andres Manuel Lopez Obrador has long preached a Mexico-first stance, accusing its government of servility to Washington and lambasting the free trade that he says has devastated his country鈥檚 farms and workers. U.S. President Donald Trump鈥檚 call to reduce U.S. economic ties with Mexico meshes with his demand to make Mexico less reliant on America.

Some have speculated that if Trump threatens to scrap the North American Free Trade Agreement, Lopez Obrador as president would simply say 鈥済o ahead鈥 with a smile. While the candidate has toned down his criticism of the trade pact ahead of Mexico鈥檚 July 1 presidential election, and even expressed some support for it, how he would handle the renegotiation of NAFTA by the U.S., Mexico and Canada is a great unknown.

Adding to the potential combustibility of U.S.-Mexico ties, Lopez Obrador like Trump doesn鈥檛 shy from an insult or from Twitter. And both have campaigned as outsiders, Trump talking of 鈥渄raining the swamp鈥 in Washington, while Lopez Obrador rails against 鈥渢he mafia of power鈥 that rules Mexico.

鈥淚t would be a strange relationship, one never seen before,鈥 said Jose Fernandez Santillan, a political science professor at the Technological Institute of Monterrey, a leading Mexican university. 鈥淚t would be two completely different nationalisms: the right-wing nationalism of Trump and the left-wing nationalism of Lopez Obrador.鈥

It is Lopez Obrador鈥檚 third bid for Mexico鈥檚 presidency and his supporters still claim he lost the first time through vote fraud, fuelling the divisiveness of his current campaign. After that loss in 2006, his supporters blocked streets in Mexico City during months of protests and Lopez Obrador referred to himself as the country鈥檚 鈥渓egitimate president.鈥

Now 64, the Morena party candidate has moderated his policy proposals, saying he wants to make friends not enemies, but he still insists he is the same as before.

鈥淚 am never going to change. That is what is most important to me in my life: my honesty, my authenticity,鈥 Lopez Obrador says.

In a country obsessed with government corruption and unfulfilled promises, he is widely believed to be the least compromised candidate and his vows to never change feed his popularity, analysts say. Add to this his irascible manner, folksy campaign phrases, stiff-necked refusal to negotiate and insistence in his own personal honesty, and the result is an almost cult-like following among his supporters.

When he was mayor of Mexico City in the early 2000s, he fed this straight-talking, man-of-the-people image by flying tourist class and driving a Nissan compact.

鈥淗e remains the same. He is a person with humility and he will stay that way, even if he wins the presidency,鈥 said Silvia Rodriguez, a homemaker with three children who travelled in from the Mexico City鈥檚 poor suburbs to attend one of Lopez Obrador鈥檚 rallies. 鈥淗e is a man of the people and he will fight for the people.鈥

However heroic, it is a stance that often leaves him looking vaguely alone and self-obsessed, with some critics even calling him messianic.

In the introduction to a new documentary about his life, Lopez Obrador is accompanied on a trip back to his hometown by old friends and supporters. But they never speak in the documentary and his former neighbors are barely allowed a phrase. There are photos of his brothers but he is estranged from most of them. The title of the documentary? 鈥 鈥淭his is me.鈥

Lopez Obrador has a strong lead so far in polls, but the election is still more than six months away and the campaign is shaping up as a first-past-the-post race involving at least three and perhaps five prominent candidates. And he can be prone to campaign gaffes. He recently generated a spasm of press ridicule by suggesting the possibility of an amnesty for drug cartel leaders.

Despite Lopez Obrador鈥檚 penchant for verbal combat with his opponents, he has so far been remarkably restrained when speaking of Trump, whose reference to Mexicans as rapists and criminals has made him an easy target here. Immediately after the Republican candidate鈥檚 victory, Lopez Obrador called it 鈥渢his uncomfortable reality,鈥 but added: 鈥淭here is nothing to fear. Let鈥檚 go forward.鈥

His platform, too, steps away from confrontation. 鈥淲e want to be friends. We will ask for a new dialogue, starting from a standpoint of cordiality and mutual respect, as good neighbors,鈥 it says.

But Lopez Obrador is touchy about efforts to label him a left-wing Trump. He narrowly lost the presidential elections in 2006 and 2012 after rivals compared him to another leader unpopular in Mexico, Venezuela鈥檚 Hugo Chavez.

鈥淭hey are trying to scare people by calling us populists, or comparing us to (current Venezuelan President Nicolas) Maduro or Trump,鈥 Lopez Obrador said in a videotaped message in June. 鈥淭ell them to take a walk, don鈥檛 be afraid. Change is going to be peaceful and orderly. The only thing we want is to end corruption, for people to have jobs, to have public safety, to have well-being for everyone.鈥

While he often speaks as a firebrand, Lopez Obrador governed as a moderate as mayor of Mexico City, keeping good relations with the private sector and the Roman Catholic Church.

鈥淚n power, Lopez Obrador certainly looked more like a pragmatic, left-of-center politician than Hugo Chavez,鈥 said Federico Estevez, a political science professor at the Autonomous Technological Institute of Mexico. 鈥淗e was not particularly ideological in most of his policy. You could do business with him.鈥

Where Trump and Lopez Obrador most agree is on skepticism about NAFTA. Both have called for renegotiating a deal they say has harmed the working class in their countries.

Trump wants to increase U.S. content in automobiles under NAFTA rules and stem the migration of auto plants to Mexico. Lopez Obrador would ban foreign ownership of oil and energy resources and try to make Mexico more self-reliant 鈥 in part by pushing for greater reinvestment in the state oil company in order to cut fuel imports from the U.S.

Still, while he blames the treaty for devastating Mexican farmers, Lopez Obrador now says that 鈥淣AFTA, with all its defects 鈥 and it has them 鈥 has proved to be a useful instrument for developing commercial and economic relations.鈥

Historian Lorenzo Meyer noted Lopez Obrador is campaigning to solve the very problems that have made Mexico such an easy target for Trump 鈥 鈥渋ts corruption and inefficiency, for having sent millions of Mexicans abroad.鈥

Lopez Obrador鈥檚 foremost promise is to combat corruption, which is a popular rallying cry in country where graft, kickbacks and outright theft by politicians is a huge problem.

鈥淕iven that our business and political elite have nothing to offer but more of the same, that is, what they鈥檝e been doing for 25 years ... Lopez Obrador doesn鈥檛 have to offer much,鈥 Estevez said. 鈥淗e just has to sit back and let things unravel and say that he is the only one out there that would be able to stop the unraveling, put things back in order.鈥

Associated Press writer Peter Orsi contributed to this report