MEXICO CITY >> Hundreds of federal police blocked highways in and around Mexico’s capital today in open revolt against plans to absorb the officers into the newly formed National Guard, a move that the police fear could upend their jobs.

The protests came as the government officially began deploying the National Guard to try to seal the country’s porous southern border and control immigration and crime. The demonstrations threatened to complicate the formation of the new force, which President Andrés Manuel López Obrador has bet Mexico’s future security on.

Uniformed officers blocked a major expressway in front of federal police offices in the capital, and another contingent blocked the highway between the city and the Hidalgo state capital of Pachuca. Federal police at a Mexico City command center demanded a meeting with the security secretary.

The president has been dismissive of the federal police, characterizing them as a failed security force. He gave military officers the bulk of the responsibility for the National Guard. The new agency is also seeking new recruits.

Late today, López Obrador suggested many of the protesters are officers who can’t pass vetting or physical exams. He said the force had become “rotten” and “perverted” and “from top to bottom, the rule was irresponsibility and corruption.” He also suggested there were ulterior motives behind the protest, but didn’t explain that accusation.

Protesting police at the command center in the capital’s Iztapalapa borough said their seniority, rank and benefits would not be recognized within the National Guard.

National Guard Commandant Patricia Rosalinda Trujillo Mariel, one of the few leaders of the new force who came from the federal police, was jostled by the crowd as she arrived to meet with the protesters and asked them to put forward representatives to talk.

“I am federal police. I respect the principles of my institution, and I want to have a dialogue,” Trujillo shouted over the crowd.

Police officer Alejandra Baez Villanueva said the police need their jobs to support their families.

“We aren’t protesting. We’re just demanding our rights,” she said. “We just want them to respect our seniority, because for (members of) the army and the navy, they respect it, and for us as federal police they don’t.”

Speaking later at a news conference, Mexico’s security secretary, Alfonso Durazo, assured that the government would respect officers’ seniority, salaries and benefits. He said federal police should not worry because those who do not want to join the National Guard will get jobs with other government entities. He blamed misinformation for sparking the demonstrations.

“No transition is simple, and this one is no exception,” Durazo said.

He also highlighted what could be an improvement for police who join the National Guard. He said they would be based in various locations around the country and work in those areas rather than being constantly deployed for operations all over Mexico as the federal police were.

In front of federal police offices in Mexico City, uniformed officers blocked the Periferico expressway, backing up traffic for a time. More than 100 uniformed officers also blocked the highway connecting the capital and Pachuca near Ecatapec. Traffic backed up for miles in both directions. Some bus passengers walked from one side of the blockade to the other looking for other transportation.

The demonstrations revealed a vast difference in culture between the federal police and military. When federal police officers are deployed, they are typically put up in hotels. When the military operates outside its bases, soldiers sleep wherever available and receive little compensation to cover their meals.

Last week, the newly appointed head of the National Migration Institute apologized for calling some federal police officers “fifi,” or posh, when they complained about difficult conditions in the effort to reduce the flow of migration through Mexico toward the United States.

Mexico sent 6,000 National Guard troops to the southern border to assist in that effort, and thousands more have been deployed on the northern border to deter illegal border crossings.

Before dawn today, National Guard agents appeared on the banks of the Suchiate River in Ciudad Hidalgo, Chiapas, where they supported immigration agents checking the documents of foreigners crossing the border from Guatemala on rafts. Dozens of migrants were loaded into vans, including 12 peoples from Bangladesh who the Guard said were caught crossing on rafts.

A National Guard commander explained to the agents that they were there to support immigration enforcement, but not to interfere in the brisk and vital commerce carried out on rafts that shuttle all manner of goods between the two countries. The show of force came the same day as media were invited on a tour with National Guard troops in southern Chiapas.

The crackdown, sometimes using military and police personnel, actually began weeks ago. Since May 17, officials said, 20,400 migrants had been detained on the southern border. They estimated there were 61 unregulated border crossing points in the border state of Chiapas.

Critics say the immigration enforcement mission could distract the force from its primary responsibility of curbing violent crime.

Mexico is experiencing the highest number of killings in at least 20 years, though the rate of the slayings has stabilized in recent months. For years, Mexico relied on the military to confront organized crime, in some cases even disbanding local police forces because they had been infiltrated by cartels.