SAN FRANCISCO -- Supporters of a controversial November ballot measure that would decriminalize prostitution in San Francisco Wednesday called the proposed legislation "a transformational change" from the prosecution of sex workers to their protection.

"Prop. K aims to increase women's safety and make it easier for sex workers to report violence without fear of arrest," said Rachel West of US Prostitutes Collective, an organization that campaigns for decriminalization.

West, responding to allegations earlier in the day by Mayor Gavin Newsom and District Attorney Kamala Harris, said the measure supported the prosecution of human traffickers in the sex trade but not the arrest and possible deportation of sex workers.

Newsom and Harris argued the measure, which would prohibit local law enforcement from using funds to investigate and prosecute prostitution, would attract pimps and sex traffickers to San Francisco.

"We can not give a green light or a pass to predators of young women," Harris said.

"This is so much bigger than what happens between consenting adults behind closed doors," she added.

Prosecutors believe disallowing law enforcement from prostitution arrests could impede trafficking investigations.

"Very often, the way in which cases of human trafficking are brought to light is through investigations of prostitution," said District Attorney's Office spokeswoman Erica Derryck.

The measure requires a majority vote for passage.