Alliance for Justice is a leader organization ensuring non-profits rights to engage in advocacy are protected. They provide training, technical assistance, and resources to non-profits as they participate in the democratic process. To see resources they make available, go to Bolder Advocacy.
Materials on lobbying rights and laws for non-profits:
Training video on Lobbying Rules for Non-profits
Influencing Public Policy in the Digital Age
PA Lobbying Disclosure
State Lobbying Registration Thresholds