SACRAMENTO (CBS/AP) — Opponents of California’s new vaccine law have been cleared to begin collecting signatures to recall the legislation’s author.

The California secretary of state says advocates can begin collecting signatures in Sacramento and Yolo counties for the recall of state Sen. Richard Pan.

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The Sacramento Democrat and pediatrician led the drive this year to make vaccinations mandatory for nearly all California schoolchildren.

Pan’s bill, SB277, drew thousands of protesters to rallies at the state Capitol, but it eventually passed. Gov. Jerry Brown signed it into law in June.

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The Sacramento Bee reports that proponents will need nearly 36,000 signatures from registered voters in Pan’s district by Dec. 31 for the recall to proceed.

A separate statewide ballot initiative that would invalidate the law has also been cleared to collect signatures.

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