Follow The Money API

From their site: Money in state politics plays a pivotal role in shaping public policy in individual states and across the nation. The nonpartisan Institute on Money in State Politics tracks contributions in all 50 states and makes this data easily searchable online…The Institute collects campaign-finance data for state-level candidates, party committees and ballot-measure committees in all 50 states. Each two-year election cycle, data-acquisition specialists compile more than 90,000 disclosure reports from more than 16,000 candidates in the states and process more than 3.2 million records of contribution information.