MEXICO CITY — Mexican federal police officers are mutinying over the government’s decision to make them part of the country’s new National Guard, a powerful challenge to President Andrés Manuel López Obrador as he tries to fight rising crime.
Earlier this year, faced with record-setting homicide rates, Mr. López Obrador announced he would combine the navy, army and federal police into a new security force to curb violence and fight organized crime.
Now just days after the new National Guard began to be officially deployed across the country as the centerpiece of Mr. López Obrador’s security plan, police officers have rebelled.
The officers say that their pay and benefits will be cut and that they could be fired if they refuse to join. They also say they face poor conditions on deployments away from home and worry that they will serve under military commanders who do not understand civilian policing.
On Thursday, for a second day, several hundred police officers barricaded themselves inside the main police command center in the eastern part of Mexico City in protest. An angry crowd shouted approval as a group of officers held an impromptu news conference to condemn the force’s treatment by the government.
Another group blockaded one of the main highways leading north out of Mexico City and briefly blocked a second highway.
The federal police had threatened a national strike on Thursday, but there was no sign the unrest had spread outside Mexico City.
The images of the federal police in open rebellion appeared to rattle the government.
“This a movement that has no reason to exist,” Mr. López Obrador said. “It is not a just cause, because there are no firings, because salaries and benefits are not being taken away. Entry into the National Guard is voluntary.”
But the mood at the federal police compound on Thursday was defiant.
One officer, Engelbert Ruiz, stood amid the angry crowd gathered outside the main police building and said the president was not telling the truth.
“I have been asked by my superiors to send lists of dozens of officers who are supposed to show up for the evaluations at military headquarters, no questions asked,” Mr. Ruiz said. “No one is being asked if they are O.K. with it or not.”
“What is really happening,” he said, “is that they are simply changing our uniforms. With no explanations, clarity, no rights or guarantees.”
Since former President Felipe Calderón first sent the military onto the streets to fight drug gangs a dozen years ago, governments have promised that the military presence would be temporary, until local and federal police forces could be trained to replace them.
Mr. Calderón placed much of his emphasis on the federal police. His government recruited college graduates and sent investigators abroad for training. But under his successor, Enrique Peña Nieto, the effort to professionalize the police lapsed.
Mr. Lopez Obrador, by merging the federal police into the National Guard, has suggested that its officers are ill-disciplined and that their commanders are corrupt. On Thursday, he reinforced that message.
“We have always said that this police force has been going bad, and what happened yesterday is evidence of that,” he said, referring to the first day of protests.
Police officers defended their discipline, and said they were being deployed at random, with no concern for their families.
“I am protesting and fighting here for my kids,” said Officer Leticia Hernández. “It’s our lives on the line, not theirs.”
Raymundo Riva Palacio, a columnist who follows security issues, wrote Thursday that the rebellion had been gestating for months.
“No respect was shown to an institution that for years has been in the front line of fire against criminals,” Mr. Riva Palacio wrote in El Financiero, a daily newspaper.
The catalyst for the rebellion was the news that the federal police would be absorbed directly into the defense ministry, Mr. Riva Palacio wrote, which would mean that they would lose many of their benefits.
“The authorities hope that they can put down the revolt and that could be the immediate solution,” he wrote.
The damage, he warned, would persist: “This crisis favors the criminals.”