The group Protect App-Based Drivers & Services began turning in signatures to local county registrars of voters in California. The signatures are needed to place a ballot measure before that state’s voters that would allow drivers for Uber Technologies Inc., Lyft Inc. and others to remain independent contractors even under California’s AB 5 measure, which makes independent contractor classification more difficult.

Last month, the group announced it received 1 million signatures to place the measure on the state ballot. It had needed just 623,212.

Backers of the coalition include human cloud firms Uber, Lyft, DoorDash, Instacart and Postmates.

But the ballot measure is facing some resistance. San Francisco County Supervisors Gordon Marr and Matt Haney wrote an opinion article in the San Francisco Examiner newspaper on Monday calling for the human cloud firms to drop their support of the measure against AB 5.