Bloody war on drugs isn't working, admits Mexico's presidential front-runner Enrique Peña Nieto

Leading contender for July election vows to scale back assault on country's powerful cartels

Less than three weeks from voting day in Mexico's increasingly tense presidential contest, front-runner Enrique Peña Nieto of the Institutional Revolutionary Party (PRI) is signalling he would throttle back on the state's militarised assault on the drug cartels in hopes of lowering violence across the country.

His comments coincided with the last of two televised debates on Sunday which was preceded by a raucous march through downtown Mexico City by an estimated 90,000 protesters, many of them students dedicated to blocking his and the PRI's path to victory on 1 July.

The war on drugs is casting a dark shadow over an election that would otherwise mostly be about jobs, the economy and social conditions. Launched by President Felipe Calderón six years ago when he took office, it has unleashed successive spasms of violence and cost the lives of nearly 50,000 people.

Mr Calderón's determination to take on the cartels, which has come to define his presidency, was welcomed by the United States, where almost all of the trafficked drugs are consumed. Any suggestion the election of a new president – Mr Calderó* is barred from running for a second term – will bring a backing away from the fight will sound alarms in Washington. Mr Peña Nieto's lead in the polls has started to slip, in part thanks to misgivings being voiced by Mexico's students, about returning the PRI to Los Pinos, the presidential palace. The party is remembered for its autocratic style when it held the presidency for 70 years, from 1929 to 2000, and its reputation for corruption and, allegedly, its willingness to turn a blind eye to the drug barons.

But none of the main candidates have endorsed the anti-drugs strategy of Mr Calderón notably his decision to deploy the military to back up the weakened and often corrupt police forces. Eager to promise a return to calm and security, they have instead promised to return the job to the police. "The adjustment in the strategy is to focus on decreasing violence," Mr Peña Nieto told The New York Times. "And that means the whole Mexican state, jointly between the three levels of government – state, federal and municipal – should focus its efforts on combating homicide and the impunity it is a given in many homicides committed, as with kidnapping and extortion."

Josefina Vazquez Mota, of the governing National Action Party (PAN) has slipped to third position in most polls, while Andrés Manuel López Obrador of the leftist Party of the Democratic Revolution, PRD, has climbed to second and may be closing in on Peña Nieto. With the backing of students, he has faulted Mr Calderón for doing the bidding of the US in tackling the drugs issue.

"We're going to stop the war (against organised crime) and there will be procurement of justice," Mr López Obrador said recently. "We are not going to use this strategy, because it has not produced results. There will be employment, we'll battle corruption and calm down the country, we know how to do it."

The mobilisation of students against Mr Peña Nieto began last month when a campaign appearance at a Mexico City university dissolved into chaos as students heckled him and he had to shelter in a toilet. He was later mocked by Ms Mota. "Mr Peña Nieto, we don't want someone who is going to hide in the bathroom of a university to solve the country's problems and belonged to a party that tolerates corruption," she said.