BUCHAREST, Romania — After five straight days of spirited mass protests, and predictions that a half-million or more people might take to the streets on Sunday, Romania’s month-old government backed down Saturday and withdrew a decree that had decriminalized some corruption offenses.

“We will hold an extraordinary meeting on Sunday to repeal the decree, withdraw it, cancel it,” Prime Minister Sorin Grindeanu said late Saturday evening.

It was a remarkable and rapid turnaround for a government that had shown every sign of holding firm against the protests.

As recently as Thursday, Mr. Grindeanu said, “We took a decision in the government and we are going to press ahead.”