In the capital and beyond, moderates applauded the move, saying it was little more than a hollow promise that would cost the state some $400 billion a year.

But one response that ricocheted around social media made it clear how infuriated some liberals were by his decision. In an adaptation of California’s state flag, the image showed a knife brandishing the name “Rendon” stabbing a grizzly’s back.

The image was initially sent out by RoseAnn DeMoro, the executive director of the California Nurses’ Association, who had been the legislation’s most ardent and vocal supporter. The nurses’ union urged supporters to flood Mr. Rendon’s office with calls objecting to his move and held a protest outside his Los Angeles office Tuesday. It plans a similar demonstration in Sacramento on Wednesday. Liberal luminaries including Van Jones, Michael Moore and Senator Bernie Sanders of Vermont (whom Ms. DeMoro backed) harshly criticized Mr. Rendon.

Despite the outcry, Mr. Rendon has so far made no attempt to apologize or backpedal from his actions. Instead, he has gone on the offensive, saying in a series of interviews that the bill was irresponsible because it did not include details about how the state would pay for the program.

“We were presented with an underdeveloped bill to say the least, and it was not even a real bill, it was a statement of values,” he said by phone Tuesday, calling the anger directed at him “misplaced.” “In California we’re the cornerstone of progressive values. This single bill should not be seen as the yardstick for how we measure progressives.”