Carl Krawitt, left, a supporter of a measure requiring nearly all of California school children to be vaccinated, answers a question during news conference at the Capitol in Sacramento, Calif., Wednesday, April 15, 2015. Krawitt's said he had worried about son Rhett, 7, center, who was unable to be vaccinated while receiving treatment for leukemia. At right is Assemblyman Marc Levine,B-San Rafeal, a supporter of the measure and whose district the Krawitts live. The state Assembly is expected to vote on the bill, Thursday. (AP Photo/Rich Pedroncelli)

SACRAMENTO, Calif. |  California’s Assembly on Thursday approved a hotly contested bill requiring that nearly all public schoolchildren be vaccinated, clearing one of its last major legislative obstacles before the measure heads to the desk of Gov. Jerry Brown.

The bill aims to increase immunization rates after a measles outbreak linked to Disneyland in December sickened over 100 people in the U.S. and Mexico.

It would give California one of the nation’s strictest vaccine laws by striking the state’s personal belief exemption. Only children with serious health issues would be allowed to opt out of mandatory vaccine schedules. Unvaccinated children would need to be homeschooled.

“Do we wait until we have a full-fledged crisis to protect the most vulnerable?” Assemblywoman Lorena Gonzalez, D-San Diego, asked as she presented the bill.

The measure passed on a bipartisan 46-30 vote after weeks of vocal opposition, with thousands of parents donning red shirts to protest at the Capitol. Two Republican assemblywomen joined the Democratic majority in support.

The Senate already approved the bill once, but still must approve amendments before it is sent to Brown, a Democrat.

Brown has not said whether he would sign the bill authored by Democratic Sens. Richard Pan of Sacramento and Ben Allen of Santa Monica.

Opponents of the vaccine bill have already taken out paperwork to recall at least two senators who voted for the proposal.

Sen. Bill Monning, D-Carmel, said Thursday that he and Pan have been targeted for recall. Monning said his district, which includes Santa Cruz, has a high number of parents who seek vaccine exemptions for their children and he has had to shut down his district office out of safety concerns.

Opposition was fierce during the Assembly debate. Both Democrats and Republicans spoke against the loss of parental autonomy.

“We do not have the right, nor should we have the power, to take away a parent’s right to choose,” said Assemblyman Devon Mathis, R-Visalia.

Associated Press Writer Judy Lin contributed to this story.