Obama says the proposal would help prevent special interest groups from influencing politicians and gaining clout in Washington.
The Senate is scheduled to vote Tuesday on whether to begin debate on the proposal. Democrats need 60 votes to proceed. The bill would impose new donor and contribution disclosure requirements on nearly all organizations that air political ads independently of candidates or the political parties.
The bill responds to a Supreme Court ruling that permits corporations and unions to spend their own funds on ads or other political activities.
The Senate proposal contains a contentious exemption for large organizations, including the National Rifle Association and the AARP.