Congressional Power of the Purse Act This bill modifies the budget and appropriations process to establish various requirements for federal agencies, add several new disclosure and reporting requirements, and expand congressional oversight authorities. Among other changes, the bill requires the Office of Management and Budget to release funding to agencies at least 90 days before the funding expires; certain presidential emergency declarations to expire within 30 days unless Congress approves the declaration; federal agencies to make various reports, documents, and legal opinions available to Congress and the public; and federal agencies to respond to certain Government Accountability Office requests within 20 days unless the request includes a different deadline.