The labor union funding California’s Billionaire Tax Act initiative filed more than 1.5 million signatures on April 27, almost double the 875,000 needed to put the measure on November’s ballot. California voters are now a step closer to driving out one of the last remaining engines of economic growth in their state, which is already losing entertainment, manufacturing, and energy jobs.

The ballot measure is sponsored by the Service Employees International Union-United Healthcare Workers West, which represents hospital staff mostly at nonprofit entities such as Kaiser Permanente, Sutter Health, and Dignity Health. It has also been endorsed by the American Federation of State, County and Municipal Employees California, Teamsters California, plus Sens. Chris Murphy (D-CT) and Bernie Sanders (I-VT), and Silicon Valley’s congressman, Rep. Ro Khanna (D-CA).