San José Mayor Matt Mahan and other local Democratic leaders on Wednesday announced their support for Proposition 36, a crime reform measure on the November ballot that they hope will force eligible Californians who routinely commit drug crimes into substance abuse treatment.

“People are dying who don’t have to die, and businesses are closing that don’t have to close. There is an answer. The answer is treatment,” Mahan said at a morning news conference announcing a new fundraising committee he created alongside two other elected officials. “That’s why we’re here today to support Proposition 36. Not because we want to go back to an era of mass incarceration, but because we want to go forward to an era of mass treatment.”

Their support runs counter to Gov. Gavin Newsom and top Democrat leaders in the state Legislature who have spoken out against the measure, fearing it would return California to an ineffective tough-on-crime era that swelled the state’s prison population to unconstitutional levels.

But Mahan, who just won reelection, said Proposition 36 will help bring necessary treatment to those addicted to the fatal drug fentanyl, by imposing a court-mandated drug treatment for those who are convicted of a drug offense for the third time. The measure will also change parts of Proposition 47, a decade-old ballot measure that downgraded some nonviolent property and drug crimes from felonies to misdemeanors to reduce prison populations.

He was one of the first big-city mayors to endorse the ballot measure, along with Mayors London Breed of San Francisco and Todd Gloria of San Diego.

Eight legislators have already endorsed Proposition 36 this week. Meanwhile, Senate President Pro Tem Mike McGuire (D-Healdsburg), Assembly Speaker Robert Rivas (D-Hollister) and various members of the Legislative Black Caucus have opposed the measure.

Mahan created the new committee to support Proposition 36 alongside Sacramento Dist. Atty. Tien Ho and Elk Grove Mayor Bobbie Singh-Allen. They have been vocal proponents of the prosecutor-led ballot initiative and draw connections to homelessness, the fentanyl crisis and the surge in retail theft, which are three cornerstones to the November ballot measure.

The Proposition 36 campaign received more than $9 million in support from major retail corporations including Walmart, Home Depot, Target, and In-N-Out Burger.