"Initiatives should be a last resort," Steinberg told reporters last month.
But the doctors' lobby is unlikely to accept a legislative deal, said Dustin Corcoran, chief executive of the California Medical Assn.
"I couldn't think of a worse time to increase healthcare costs and decrease access to care," he said.
The measure's backers have raised $1.7 million so far, mostly from law firms and individual attorneys, as well as from the advocacy group Consumer Watchdog. They have spent $800,000 circulating petitions.
Kabateck, who is leading the fundraising effort for the consumer attorneys, estimated his side would raise $10 million.
The opponents' cash advantage is already apparent. They have raised more than $33 million, including several multimillion-dollar contributions from medical malpractice insurers. Most of the haul is in the form of loans, which allows the money to be returned if the initiative does not go forward.
The doctors and their allies have been steadily raising the alarm through social media and emails to supporters. They've produced pamphlets to be distributed at physicians' offices, in English and Spanish, asserting that patients' access to affordable healthcare is under siege from unscrupulous trial attorneys.
But most of the early salvos have come from the initiative's backers, who paid for billboards criticizing the pain-and-suffering cap and advertising a toll-free number to report drug- and alcohol-impaired doctors.
They're also sending elected officials graphic videos about victims of malpractice. One is Annette Ramirez, a South Bay mother of two who underwent an elective hysterectomy in 2012 and ended up losing her arms and legs due to infection after her colon was perforated during surgery.
Ramirez sued her hospital and eight doctors for malpractice; her case was ultimately settled.
"Two hundred fifty thousand dollars is not going to cover my pain and suffering, ever," Ramirez said, adding that the cap is "almost an insult."