(Reuters) – U.S. Senator Barbara Boxer endorsed a proposed California ballot initiative on Monday to raise the state's cap on medical malpractice awards, the first salvo in a political fight between lawyers backing the measure and doctors who oppose it.

Consumer advocates in the most populous U.S. state submitted signatures last week to place a measure on the November ballot that would raise a four-decade-old state cap on medical malpractice awards to $1.1 million, from $250,000.

"I will never forget meeting a child who was severely disfigured and forever confined to a wheelchair because of medical malpractice," Boxer, a Democrat, said in a statement sent to Reuters by proponents of the measure and confirmed by her office.

"I was stunned to learn how unfair California law is in terms of compensating these patients and their families," she said.

In addition to raising the cap on pain-and-suffering awards, the initiative would require random drug testing of doctors in the wake of growing concern about over-prescription of addictive pain medications, including among doctors, said Jamie Court, president of the non-profit Consumer Watchdog. The group is sponsoring the initiative along with Consumer Attorneys of California, the state trial lawyers association.

Representatives of patients have tried for at least 20 years to persuade the state to raise the limit on pain-and-suffering awards, which was set in the 1970s and is not indexed to inflation. Opposition from the California Medical Association and other representatives of doctors have made such changes difficult to enact.

A spokeswoman for the California Medical Association reached on Monday morning said she would seek comment from initiative opponents on Boxer's endorsement of the measure.

Last week, CMA president Richard Thorp said lifting the cap would make health care costs rise even further, as doctors were forced to spend more on malpractice insurance.

"This is a flawed and dangerous measure that's going to increase lawsuits raise health costs and reduce health access everywhere in our state. Californians don't want it because California can't afford it," Thorp said in a statement.

Opponents include not just doctors, but also medical providers such as clinics and hospitals, spokeswoman Molly Weedn said.

Hoping to avoid a costly and ugly battle between doctors and lawyers over the ballot initiative, state senate Democratic leader Darrell Steinberg last month introduced a bill saying it was the legislature's intent to bring both sides to the table and try to reach a compromise.

But although representatives of doctors and lawyers came close to agreeing on a deal proposed by Steinberg to raise the limit under the Medical Injury Compensation Reform Act, or MICRA, to $500,000, the talks fell apart.

Proponents said last week that they had gathered 844,000 signatures in support of placing the measure on the ballot, far more than the nearly 505,000 required by state law. The signatures must be verified by the Secretary of State before the measure can proceed to the ballot. (Reporting by Sharon Bernstein; Editing by Cynthia Johnston and Andrew Hay)