SAO PAULO (AP) — Brazilians took to the streets on Friday to protest a new labor law and proposed changes to the social security system that they say will make people work longer and with fewer rights.

Labor Minister Ronaldo Nogueira said the new work rules, which go into effect Saturday, will bring much-needed modernization to Brazil's labor market and create jobs and growth as the country recovers from a deep recession. But they remain deeply unpopular.

Thousands of union members, students and artists protested the reforms and other elements of President Michel Temer's agenda in downtown Rio de Janeiro on Friday evening, frequently shouting "Out with Temer!" During the morning commute, some demonstrators set fire to a car they parked on the bridge that spans the city's Guanabara Bay. Next to the car, a banner read: "Rotten power. The worker resists."

Trade unions called for a day of action around Brazil, but most protests remained relatively small. In Sao Paulo, several hundred people marched from a central square to a major avenue.

"No one is going to be able to retire, so it's really imposing modern-day slavery," said Sergio Ricardo Goncalves da Silva, 45, who works in a candy store and was protesting in Sao Paulo with a fake ball and chain draped around his neck.

One of the labor law's signature changes will allow negotiated agreements between employers and workers to override current labor protections. Supporters say that will provide much-needed flexibility; critics say it will pressure vulnerable workers to cede important rights.

The pending pension overhaul, meanwhile, would set a minimum retirement age, ending a system in which workers can retire solely based on the number of years worked. It would require most people to work longer to receive full benefits.

Currently, some workers can retire in their 50s with nearly full benefits.

Temer's administration has already agreed to loosen its original proposal and says it is willing to negotiate even more changes to get it passed.

But it's unclear if that will be enough.

Temer has spent significant political capital to gain support for other parts of his agenda and to survive two congressional votes that could have suspended him and put him on trial on corruption charges. With national elections less than a year away, lawmakers may be even less likely to support an unpopular reform championed by a president whose popularity is in single digits.

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Associated Press producer Yesica Fisch and photographer Silvia Izquierdo contributed from Rio de Janeiro.