Officials in famously progressive San Francisco have long sanctioned protections for people in the country illegally, going so far as to prohibit city workers from asking about a person's immigration status.

But the deadly shooting of a woman along a popular pier last year and the arrest of a Mexican national sparked a national debate over how the city handles such criminal suspects.

The sheriff at the time cited the law in defending the release of the man, a repeat drug offender and habitual border crosser. He lost his re-election bid to a candidate who said she would have considered greater communication between the city and federal governments.

The Board of Supervisors had planned to address the division on Tuesday with a vote on whether to reaffirm its strict protections and spell out when immigrants can be turned over to the U.S. government.

But supervisors postponed voting on a proposed ordinance directing law officers to notify Immigration and Customs Enforcement only if a defendant is charged with a violent crime and has been convicted of a violent crime within the last seven years. That would be the only time city workers, including police officers, could disclose immigration status.

Supervisor John Avalos, the proposal's sponsor, said he didn't want to vote without support from San Francisco Sheriff Vicki Hennessy, who is opposed. Avalos said he expects her to compromise.

The sheriff, as a constitutionally elected official, does not have to follow board orders. But her stance puts her at odds with the supervisors and other officials who have largely supported the sanctuary law for decades.

"I don't think she can withstand sitting as an outlier in San Francisco government that doesn't uphold the values of a sanctuary city," he said.

Eileen Hirst, the sheriff's chief of staff, said Tuesday that the sheriff "is happy to continue the conversation."

The vote will be postponed at least two weeks.

The killing of 32-year-old Kate Steinle in July and the arrest of Juan Francisco Lopez-Sanchez put San Francisco's leaders on the defensive as critics and outside politicians called for a change in the so-called sanctuary law.

It's not clear, however, whether Lopez-Sanchez would have been held for federal pickup under the criteria of Hennessy.

"I'm not going to say with certainty, but what I can say with certainty is that he would have been looked at," Hennessy said before the meeting Tuesday.

Sanctuary advocates say a clear division between local law enforcement and federal immigration authorities is needed to foster trust.