Mexico's embattled President Enrique Pena Nieto will unveil Thursday a plan to combat corruption in a bid to contain a crisis over the apparent massacre of 43 students by a police-backed gang.

Pena Nieto has faced a wave of angry protests since the students, all aspiring teachers,  were rounded up by municipal police in the southern state of Guerrero two months ago.

The case has become a tragic example of collusion between local authorities and organized crime in Mexico, a country struggling with drug violence that has left 100,000 people dead or missing since 2006.

On the eve of his announcement, Pena Nieto said the crime in Guerrero was a "turning point for the nation."

"It is only a constructive, positive attitude that will allow us, society and government, to build the Mexico that we want and that we want to project to the entire world," he said.

Pena Nieto is expected to push for passage of dormant anti-corruption legislation and announce an overhaul of the country's municipal police forces.

Prosecutors say the mayor of the city of Iguala ordered his police force to confront a group of students over fears they would disrupt a speech by his wife on Sept. 26.

Guerreros Unidos gang henchmen confessed to killing the students and incinerating their bodies after officers turned them over.

Pena Nieto will not be the first Mexican president to seek to reform the police.

Some 400,000 federal, state and municipal police forces across the country have undergone anti-corruption exams with polygraph tests, a system that began under his predecessor, Felipe Calderon.

The interior ministry said this month that 13 percent of municipal officers failed the exam, compared to 10 percent of state and 6 percent of federal forces.

The non-government organization Common Cause said this week that 42,214 federal, state and municipal police members are still working despite failing the "control de confianza" (trust test).

"We have made it clear to governors ... that they must remove them from their positions," Interior Minister Miguel Angel Osorio Chong. "None of them can be in the streets today, in any state, in any town."

When he took office in December 2012, Pena Nieto vowed to reduce the everyday violence besetting the country.

But he maintained the controversial militarized strategy of Calderon, who deployed 50,000 troops against the drug cartels in 2006.

Pena Nieto launched a crime prevention program, which officials acknowledged will take years to show results, and created a 5,000-strong militarized police force, the gendarmerie.

In an editorial, the national daily El Universal noted that past governments launched anti-crime measures in response to public discontent, with some positive results.

"But the depth of the problem is so large that these actions have not changed an indisputable fact in the perception of people, that crime continues to grow," it said.

"This time, the State's response will have to be stronger."