Federal judges voted on Monday night to go on strike across Mexico, protesting President Andrés Manuel López Obrador’s proposed overhaul of the country’s judicial system. The judges will join thousands of other court employees who went on indefinite strike earlier in the day over the contentious policy changes.

The moves reflect rising tensions over Mr. López Obrador’s push for the most sweeping changes to Mexico’s legal system in decades. He and his supporters want thousands of Mexico’s judges, including those on the Supreme Court, to stand for election instead of being appointed based on qualifications and specialized training.

Mr. López Obrador has defended the plan, arguing that the ultimate goal is to rid the judiciary of “corruption and privileges.” Critics say the change could result in people with minimal legal experience being elected to judgeships.

The president “has lost it,” said Juana Fuentes, the national director of Mexico’s association of federal judges and magistrates, which organized the strike vote. “If this bill passes, we will be creating a regime of absolute power concentrated in one single person.”

The vote means that on Wednesday, more than 1,400 judges and magistrates will join the federal court workers who walked off the job on Monday.

Mr. López Obrador is hoping to push his measures through in September, his last month in office, when Congress reconvenes. With the combination of lawmakers from his Morena party plus allied lawmakers, the president is expected to have a large congressional majority.