San Francisco’s supervisors sparred Tuesday over a bill by state Sen. Scott Wiener that tackles one of the most pressing issues among voters: conservatorship programs to get mentally ill and drug-addicted homeless people off the street.

Wiener’s bill, SB1045, would give counties more control over those programs. Under state law, counties can hospitalize people for 72 hours only if they pose a danger to themselves or others. The supervisors defeated a resolution to support it, after the five progressives said they weren’t ready to take a position.

“I’ve heard from people who say the bill loosens the standard for conservatorship,” said Supervisor Norman Yee, one of the five “no” votes. The resolution sponsored by Supervisor London Breed needed eight votes to pass because it was brought to the board without a committee hearing.

Breed praised Wiener’s approach, saying the current law, written in the 1960s, is archaic and frustrating. Moreover, it doesn’t allow cities to compel treatment for people using psychoactive substances other than alcohol, she said.

She said that nearly half of all psychiatric emergency room visits in San Francisco involve methamphetamine use, not alcohol.

“We cannot watch people languish like this,” Breed said. “Under current law we can’t adequately intervene.”

Breed is in the last sprint of a tight race for mayor against Supervisor Jane Kim, who was forced to take a stance on the contentious conservatorship issue when Breed brought the resolution before the board. She was among the dissenting votes.

Yee and Supervisors Hillary Ronen and Aaron Peskin said the resolution should be subject to a committee hearing, which would allow experts to testify.

Also on Tuesday, the board voted 10-1 against allowing the owners of the six-unit building at 670 Page St. to convert it into condominiums.

One owner, Peter Owens, drew ire from housing activists two years ago when he evicted an elderly woman, Iris Canada, from her apartment in the building. She died last year at age 100.

Owens had accused Canada of living elsewhere with family members while thwarting his conversion effort. But that argument fell flat in City Hall.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan