Can American presidents use their budget proposal authority to achieve theirown partisan policy priorities? This is an important, yet challenging,question to answer since formal executive authority is ambiguous, andbudgetary powers are shared in the US separation of powers system. Indeed,the question remains open since prior empirical designs conflate externalconstraints (arising from political and policy conditions) with those thatreflect executive partisan policy priorities. This study advances a novelstochastic decomposition of executive budget proposals in order to analyzethe extent to which presidents can shape the legislative funding of USfederal agencies consistent with their own partisan policy priorities.Statistical evidence reveals that presidents exert partisan-based budgetaryinfluence over appropriations that cannot be ascertained from previousempirical studies that rely on either the observed gap between presidentialrequests and congressional appropriations or standard instrumental variableestimation methods. The statistical evidence also indicates that presidentsare marginally more effective at converting their partisan policy prioritiesinto budgetary outcomes under divided party government. Contrary totheoretical predictions generated from bilateral veto bargaining models,presidents are also shown to exert effective partisan budgetary influenceeven when their budget requests exceed congressional appropriations.