Updated

When it comes to the presidency, Mexico's voters are fed up and ready to throw the ruling the party out. But in the nation's capital, the progressive island known as Mexico City, they're about to hand the leftist political party that has ruled since 1997 an election-day valentine.

Boyish mayoral candidate Miguel Angel Mancera of the Democratic Revolution Party, or PRD, holds an astonishing lead of about 50 points in polls going into the July 1 vote, which coincides with the presidential election.

The PRD, which is struggling in the rest of the country, expects a landslide in Mexico City because the giant metropolis that once instilled fear in Mexicans and foreigners alike for kidnapping, street crime and air pollution is now an island of calm in a country ravaged by drug violence.

Crime is down. Environmental friendly bicycles can be rented for short trips and green buses are everywhere. And progressive laws make it a Mecca for gay marriage and safe, legal abortion, both unthinkable in the rest of the conservative Roman Catholic country. A Sunday program that shuts down the city's main boulevard for bikers, rollerbladers and skateboarders has managed to create a growing sense of community even in a city this size, while the government now gives pensions to the elderly and aid to single mothers.

"There has been a change, to a more liberal, more progressive city," said Eva Villarreal, who grew up in Mexico City and now works as a television executive. "It's not so much as a question of political consciousness, but rather what benefits you as a citizen."

In the rest of the country, voters are tired of the drug violence that has killed more than 47,500 people and the lack of economic opportunities. They are so desirous of change that they're poised to give the presidency back to the old guard, the Institutional Revolutionary Party, or PRI, despite its reputation for 71 years of autocratic rule.

On the national level, they're rejecting PRD presidential candidate Andres Manuel Lopez Obrador and President Felipe Calderon's conservative National Action Party after 12 years of rule. Calderon can't run for re-election and his party's candidate, Josefina Vazquez Mota, is running third in most polls.

That leaves Mexico City as the laboratory for a new leftist current, and a counterbalance to what some fear will be a return to the dark old days of one dominant political group.

"I think that is what is coming in July, that a new project will start, to reform the progressive forces in the country," said Manuel Camacho Solis, who acts as coordinator for a broader coalition of left-leaning groups in Mexico.

Under the PRI, the president appointed Mexico City's mayor. Since the city won the right to elect its own leader, the PRD, which broke off from the PRI a decade earlier, has had a lock on the mayor's office.

The job has always been considered a launch pad for presidential politics. Lopez Obrador, who is in distant second this time to PRI candidate Enrique Pena Nieto, nearly won the presidency in 2006 after a stint as a very popular Mexico City mayor.

His successor, the popular and urbane Mayor Marcelo Ebrard tried to run this time and is a sure mention for the 2018 presidential race. Mexico City's leader can only serve one term.

The city's education and income levels, while marked by great inequality, are among the highest in the country. With the biggest concentration of university students, it also has always had the largest base of political opposition.

Mexico City also saw up close the repression and corruption that marked PRI rule before it was voted out of the presidency in 2000.

At the Tlatelolco housing project just north of the city's center, older residents still recall the hundreds killed in a 1968 massacre of student protesters there, and the hundreds more killed in the 1985 earthquake when a government-built apartment block collapsed because of sub-standard construction.

In the 2012 mayoral race, Mancera is campaigning on his reputation as the city's attorney general and a 12 percent drop in crime from 2010 to 2011. Federal figures show that under his entire term between 2007 and 2011, homicides were down by about 4 percent, and kidnappings fell by over 50 percent, even as the rest of the country saw a rise in such crimes.

While the capital continues to have a fifth to a quarter of the country's violent robberies, far outstripping its share of the population, it hasn't had the massacres, mass graves or wild drug gang shootouts seen in other parts of the country.

Mancera's main opponent, Beatriz Paredes of the PRI, touched the most sensitive defect of the PRD, petty corruption and bribery of people needing city permits.

"It's obvious that overcoming corruption in Mexico City is an enormous challenge," Paredes said in a recent debate, "and that implies overcoming the mafias that make their nest in the PRD."

The low-key, seemingly unflappable Mancera shrugged it off, partly because the PRI's own reputation for corruption is legendary, but also because he is not a PRD, having worked for the party's administration but never joining. Some hope that will give him some independence.

"I don't see the need to join any ... of the parties," Mancera said, a position that seems to resonate with Mexicans tired of the country's political groups. But the tasks before him are daunting in a city that produces 9,000 tons of garbage daily and needs 16 million square yards of pavement replaced.

The very size of the city with 13,000 surveillance cameras and a 70,000-officer police force is also what keeps it fairly immune to the drug war, Mancera said. The city's contentious traffic complicates transportation and it would be hard to bribe the entire city police force, as cartels do in some smaller cities.

"Mexico City is hard for them to stage the kind of ostentatious operations they are accustomed to," Mancera said. "They operate in convoys of five or six vehicles ... that's hard to do in the city."

It also doesn't hurt that under recent PRD mayors, other bribes known as "mordidas," exacted by police officers stopping motorists for alleged infractions, seem to have dropped dramatically. The problem was once so bad that drivers kept containers of five-peso (50-cent) coins ready on their dashboards.

Now only specially designated transit officers can issue tickets using hand-held computers.

The changes are drawing voters, but so is Mancera's style.

"He's completely cool ... a modern politician," said writer Guadalupe Loaeza. "He's our George Clooney."