The interaction between lobbying and financial expansion in driving the energy transition remains an underexplored topic. This study develops a dynamic partial equilibrium model to analyze how financial development and lobbying pressure shape
the allocation of oil rents between renewable (RE) and non-renewable energy (NRE) sectors in oil-exporting economies. The model identifies a financial development threshold beyond which RE capital accumulation accelerates, but also shows that lobbying can slow or even reverse this transition by diverting oil rents toward the NRE sector. The steady-state analysis reveals a saddle-point equilibrium, where convergence to a sustainable energy mix is highly sensitive to initial conditions and institutional constraints. Using threshold regression analysis on a panel of OPEC+ countries from 1988 to 2019, the empirical results confirm the existence of a financial tipping point: while financial development initially fosters RE investment, its impact weakens beyond the threshold due to rising lobbying pressure. These findings underscore the need for policies that mitigate lobbying distortions and strengthen financial markets to facilitate a sustainable energy transition in oil-dependent economies.