BUCHAREST, Romania — Romanian anticorruption protesters were out in record numbers on Sunday evening, so distrusting of their government that they refused to accept its contrite promise the night before to capitulate to their demands and rescind a decree that had decriminalized some corruption offenses.

“Why are we still here now?” said Ana Puiu, 24, a translator joining friends on the teeming square outside the main government building in Bucharest, the capital. “Because we can’t trust this new government.”

As many as half a million protesters were in the streets nationwide, an estimated quarter of a million in Bucharest alone. Many said they would continue at least until they were convinced that the month-old government would refrain from future efforts to weaken the country’s corruption laws. And some vowed to keep up the pressure until ministerial heads roll, or the entire government falls.

“We don’t want to have to be the guardians during the night, coming out into the street to save the law,” said Mihai Georgescu, 28, an information technology engineer. “Maybe they will try again in a month.”