Aetna Inc. and other insurers that initially fought President Barack Obama’s health-care overhaul are reversing course and supporting the effort by funding a group planning to spend $100 million to help the uninsured get coverage.

Enroll America, a nonprofit created two years ago, has gathered support from the insurers that opposed the law and consumer organizations such as Washington-based Families USA that supported it. The new organization plans a broad-based educational campaign to make uninsured people aware of the health-care law’s benefits and help them sign up, said Ron Pollack, Enroll America’s chairman.