This article examines why and how a national health insurance (NHI) proposal targeting universal health coverage (UHC) in Nigeria developed over time. The study involved document reviews, in-depth interviews, a further review of preliminary analysis by relevant actors and use of a stakeholder analysis approach. The need for strategies to improve healthcare funding during the economic recession of the 1980s stimulated the proposal. The inclusion of Health Maintenance Organizations (HMOs) as financing organizations for national health insurance at the expense of sub-national (state) government mechanisms increased credibility of policy implementation but resulted in loss of support from states. The most successful period of the policy process occurred when a new minister of health (strongly supported by the president that displayed interest in UHC) provided leadership through the Federal Ministry of Health (FMOH), and effectively managed stakeholders' interests and galvanized their support to advance the policy. Later, the National Health Insurance Scheme (the federal government's implementing/regulatory agency) assumed this leadership role but has been unable to extend coverage in a significant way. Nigeria's experience shows that where political leaders are interested in a UHC-related proposal, the strong political leadership they provide considerably enhances the pace of the policy process. However, public officials should carefully guide policymaking processes that involve private sector actors, to ensure that strategies that compromise the chance of achieving UHC are not introduced. In contexts where authority is shared between federal and state governments, securing federal level commitment does not guarantee that a national health insurance proposal has become a 'national' proposal. States need to be provided with an active role in the process and governance structure. Finally, the article underscores the utility of retrospective stakeholder analysis in understanding the reasons for changes in stakeholder positions over time, which is useful to guide future policy processes.