Mexico is a proud nation with a rich distinctive history and heritage, unique in not just North America but the entire Western Hemisphere. Living next door to a much larger and wealthier superpower is guaranteed to raise issues of nationalism — as Canada's history and politics also demonstrate.

Blaming the American colossus for life's problems is all—too—easy for ambitious politicians in North America and beyond. Resentment may be a cheap trick, but it often works to mobilize voters.

However, as Mexican elections reach the high season for the July 2 presidential vote, it's increasingly clear that the outcome is being influenced by strong factors from both the north and the south.

From the north, the acrimonious immigration issue in the U.S. is fuelling negative sentiment toward the U.S. and by extension, support for leftist presidential candidate Andres Manuel Lopez Obrador, who condemns any immigration control measure by the U.S. to protect its borders.

In a New York Post essay called "Menace from Mexico,"  Dick Morris warns that if an amicable immigration solution is not reached with the Fox administration, Mexican voters were likely to turn to a confrontational, and populist, Lopez Obrador, may be elected. The leftist Mexico City mayor, known as AMLO, would in turn Mexico's economy, as well as its northern border situation, into a nightmare for the U.S.

But it may be that Mexican voters are even more buffeted by a growing awareness of trouble from the south. Venezuelan dictator Hugo Chavez has been accused of bankrolling the AMLO campaign, and even meeting secretly with Mexican leftists in the Venezuelan city of Maracaibo, which if true, are both cases of authentic meddling in Mexico's election. These accusations follow November's events, in which Mexico sent Venezuela's ambassador packing to retaliate against Chavez's crude insults against incumbent President Vicente Fox as well as against his envoy's open campaigning activities  for AMLO at the National Autonomous University of Mexico.

Mexico's conservative PAN party, which is running against Lopez Obrador, has started using those Chavez insults as campaign material in a television ad, and apparently, the impact has been so strong it's knocked AMLO out of a two—year—long lead for the presidency.  PAN's candidate, according to a new poll by Grupo GEA, a consultant in Mexico, is now in first place by a couple of points, in a 1400—person face—to—face survey of voters taken around the time the ads ran. It's within the 3.25% margin of error, and the only finding of its kind, but it shows a shift in sentiment on the Chavez factor and matches a downward trend in AMLO's overall numbers in other polls.

Why is this factor seemingly stronger than the border factor? One reason may be that very few Mexicans inside the U.S. have registered to vote for the July 2 election, despite being able to do so for the first time. One wonders if the Mexicans who intend to stay in Mexico may be a stronger voting bloc than the would—be border jumpers, and therefore more affected by the Chavez affront to national sovereignty.

PAN ran quite an amazing ad.  It played footage of a contortedly angry Chavez screaming and yelling about Fox being a lapdog of the empire (meaning the U.S.). Next to it was footage of AMLO calling Fox a screeching turkey and telling him to shut up, in a surprisingly comparable tirade to Chavez's. Voters could see up close that both Chavez and AMLO, whatever the accusations about their connection, were precisely the same kind of leader. And Mexico would be getting an angry clown of its own to match Venezuela's Chavez, with little doubt about who would be calling the shots.

I spoke to an AMLO official recently, right after the widely—read Instapundit website ran an item of this possible shift in voter sentiment, and he wasn't in a very good mood. I don't know if that was the reason, but surely a drop in a candidate's poll rankings, after so many months on top, might be a cause of crankiness.

Meanwhile, AMLO himself Tuesday denounced what he calls "the Internet campaign" against him, in a statement that follows his rage against the supposed media campaign against him. He's also called for a truce with Fox over these ads, signaling defensiveness. It may be unrelated and AMLO may still win. But suddenly he's not looking completely invincible. And Hugo Chavez is why it's happening.

A.M. Mora y Leon is a frequent contributor.