Allocation decisions are vulnerable to political influence, but it is unclear in which situations politicians use their discretionary power in a partisan manner. We analyze the allocation of presidential disaster declarations in the United States, exploiting the spatiotemporal randomness of all hurricane strikes from 1965-2018 along with changes in political alignment. We show that decisions are unbiased when disasters are either very strong or weak. Only after medium-intensity hurricanes do areas governed by presidents' co-partisans receive up to twice as many declarations. This hump-shaped political bias explains 8.3 percent of overall relief spending, totaling about USD 400 million per year.